I originally posted this in the Hardrive section but wanted to post here also because I thought maybe the problem could be the ATA100 controller...i.e. need a new motherboard?
 
I spent an entire week setting up my brother's computer:
 
Asus A7V (rev. 1.02)
BIOS 1005a
30.0Gb WD hardrive
VisionTek GeForce 2 GTS  
1Ghz Atlon T-bird  
SB LIVE! Video Card
256Mb PC133 SDRAM
Delta 52X CD-rom
10/12/?? Yamaha CD-RW
 
I'm pretty sure I followed the correct steps:
1. Installed mobo,ram,hd,cd-rom,cd-rw, floppy,videocard
2. Format and partition harddrive
3. Installed Win98 SE
4. Installed network card and accessed internet for bios 1005a and latest via4-in-1 drivers (4.26)
5. Flashed new BIOS and updated drivers
6. Performed some Windows Updates
7. Installed SB! Live soundcard
 
IDE-setup:
Primary ATA100: 30Gb WD hardrive (MASTER)
Primary ATA66: Yamaha CD-RW (MASTER)
Secondary ATA66: Delta Cd-rom (MASTER)
 
The system ran well for about a two days and then one morning I hit the power button and received, "Invalid System boot disk... insert disk and press any key" Under DOS I checked my crive and found that damn near everything was GONE! The was no Windows system directory or anything! I checked my connections, re-formatted and partitioned the harddrive, and reinstalled windows. Two days later it again dies. I'm at a total loss. My guess is the hardrive is faulty. Do any of you concur or do you suspect the mobo? I really need help because I've returned to Ohio while my brother is in Texas with a dead puter' and he's probably feeling quit pizzed right about now after spending all that money. I recommended that he return the hardrive in favor of getting a 40Gb IBM drive (everyone here seems to highly recommend IBM drives).  
 
One more thing.  I noticed that some of the directories names were in the form of ASCII characters?!  I scanned for viruses and the system was clean.  The second time it failed my brother said that there was an error regarding the SB emulation driver (couldn't be found).
 
Thanks guys!

It's probable you've got a bad hard drive or your system's running too hot and choking your drive.
 
But, I'm not sure you should run ATA100 and ATA66 drives on the same IDE channel.  Somebody correct me if I'm wrong but won't that limit your ATA100 drive to ATA66 speeds?  Put your hard drive alone on the primary channel and drop the CDs to the Secondary channel.

My A7V started behaving very strangely and it turned out to be the BIOS 1005a.
Don’t use it!!!
Get 1004c off asus.com and use AFLASH.EXE.
Only uses bios’s that are on asus’s website.
I learned this the hard way.
As soon as I went back to 1004c my computer was fine.
Some of the problems were,
 
Computer seemed unstable.
Computer would not shut down, just hang at shut down screen.
Plug and Play stopped working!
The devices in system, device properties, were all missing!
 
I was left with a computer that nothing worked, no network, no sound, 640 x 480 16 colors, yuck.
I tried reinstalling windows, all the BIOS setting I could think of then I finally gave up and formatted and still nothing worked!
As soon as I flashed the BIOS back to 1004c everything started working on the next reboot!
This was proof to me the problem was 1005a.
I Hope u have the same problem because it’s a easy fix.
Thx & Cya
 
BTW never flash the BIOS using the Asus update in windows.
It’s just too risky and I think that could be part of my problems with 1005a.
Use AFLASH.EXE in DOS, It’s super easy and a lot safer.

Hello,
 
No it is not your HDD. It is that damn MB & that ultra ata promise chip that is probably causing thre problem.
 
I have had a very similar senario happen to me. Dual boot W98SE & W2k, situation ata/66 Maxtor 40 gb 7200 rpm drive AMD I Ghz cpu on the primary ata/100 ide channel (the promise chip) cdrw & cdr drive on primary ata/66 channel 4 IDE channels in all Asus a7v mb with onboard promise ultra/100 chip.
 
I was bringing in the PC for a better CPU fan swap wanted to check if I had left a cdrom in the drives turned on the power log enough to check the drives & powered off before W98 was fully loaded.  
 
When I brought the pc back from the store the W98se os was destroyed no more reg files lost all the installed programs could not user regscan to restore another copy of the registry because only one existed from the date I had just powered on.
 
I also have a asus 7700 geforce2 gts video card, which I later found out also has intermitent freezing issuses with the asus board ( this comes from Mechwarrior 4 readme file.
 
All in all I have read Tom's site saw that he was recommending the asus a7v board & the AMD cpu & Nvidia's cards, I thought I was well informed but realized the Nvidia card the AMD cpu & the asus a7v board are really lousy together ( freezing, data corruption, weeks of frustration & 10 reinstalls later & finging out the AMD is a toaster at 56 C running temp) I have never had such issues with Intel cpu's & chipsets ,I will never again purchase an AMD chip.
 
My advice to you is to buy the Gigabyte board without ata 100 support or diable the promise chip on the board, or wait for the new Via chipset that supports ata/100 support.

OK...so is the consensus that I should try putting the harddrive on primary ATA66 IDE as MASTER, the CD-rom on primary ATA66 as SLAVE, and the CD-RW on Secondary ATA66 as MASTER?  I did try putting the drive on ATA66 controller as MASTER before my brother purchased the Yamaha CD-RW after it died the first time.  It didn't work, but I kind of expected this considering the damage was already done on the ATA100 port.  So I guess we would have to do a fresh format and install on the ATA66 port.
 
By the way, CPU temp was shown at 47deg C in the BIOS hardware monitor.
 
I'm hoping my brother is able to exchange the drive for an IBM drive.  At least that throw out one possibility- a dying drive.
 
Thanks for the advice guys.  I'll try the BIOS flash also.  I'll write back with an update in the next few days.

What is the rest of your system setup?  How similar is it to mine (my brothers)?

My system is:
 
900 Tbird @ 1 gig + copper hedgehog + Sanyo Denki 60mm
A7V + 256 MB (micron cas2) BIOS 1004c
Maxtor HD 20 GIG 5200rpm ( I know, I’m saving for the 7200 IBM
Leadtek Geforce2MX  
Linksys 10/100
Ensoniq SB card (just until I get a SW1000xg)
Mitsumi CDR CR-4804TE
USB MS optical mouse
Fong Kai 603 case + 300 watt PS
Windows 98se
 
I am very happy with my setup and most of my problems were self-induced.
I would say this computer is more stable then my Gateway PII300, at least for playing Diablo II.
If I would just stop F#$%ing with it I’m sure it would run trouble free for years to come.
Also my BIOS shows 45C and asusprobe shows 52C under load which I think is normal for Tbirds.
 
Good luck & Cya

"If I would just stop F#$%ing with it I’m sure it would run trouble free for years to come."
 
I know exactly what your saying...I just never stop trying to tweak and many times screw things up in the process.  This time however, I only want to get my brother's system up and running STABLE.  I can't afford to fly down every week to Texas to provide tech support!  I'll give your BIOS idea a try.  My brother is still lacking when it comes to computers so I hope I can convey the instructions over the phone.  Man this sucks (starting to feel a little guilty).  Maybe I should have suggested that he buy a Dell or something.
 
THanks again!

I must tell you that from what you are saying the drive is most likely the problem, but before you have your brother go out and exchange/buy a new drive don't you have any old drive to try as your primary BEFORE you change your bios?
I have the Asus A7V with an IBM DTLA-307045 and a WD WDC-AC418000D on the Promice controler(note one is 100 the other 66) with no problems or perfomance issues. The best bios by far in my HO is the 1005a for this board.
Please make sure that you do all the driver upgrades from VIA and Promice.
Good luck.
PS.
Install the OS while your drive(s) are connected to the primary IDE channel(not the Promice controller) then do the VIA and Promise driver upgrades and only after they are installed swich to the Promice controler.
A great article can be found on how to set-up the A7V at AMD Zone.