I often see posts on this subject when it happens after a rebuild or sporadically, but this happens to me systematically at the reboot after Windows upate or sometimes after a programme installation.
No further problem after switching off and restarting - never any problem between updates, so it's just annoying - any ideas?
(Sorry if the subject has already been covered, but I couldn't find any reference)
I've just checked the BIOS.
The first drive selected is the CD/DVD, but I saw that the second drive selected was in fact my external disk!
Stupid of me not to check that before posting - apologies - but what confused me was that the problem NEVER occurs during a normal boot, only after an update!
Have you an explanation why the problem is not systematic?
How the external drive came to be selected is a mystery, I certainly didn't change the BIOS. It must have been put into the first choice when I connected it.
I'll modify the BIOS now, wait for the next Windows update et let you know if it is OK.
My only explanation is that when it reboots after an update is that it doesn't shutdown completely before it restarts as opposed to a full shutdown and normal boot. I hope the problem is solved. I will appreciate the update.
Now it's worse. This is what I did:
In the BIOS setup, as I said, the hard drives listed were the USB external disk at No1 and the main disk [RAID:RAID Ary 1] at No2. I put the RAID to No1, continued the boot and it worked. I wasn't using the PC any more so I didn't try a second boot.
This morning it wouldn't boot at all.
Looking at the BIOS again, the hard drive was DISABLED in the boot order! (remember - it had booted OK after I had modified the BIOS yesterday)
Looking further, I found that the RAID device was still in the list of hard drives and Disabled was selected, but the external disk had been moved to the removable devices list (is this where it should have been, as a USB device?)
I put the hard drive back as the first boot device and it still won't boot (reboot and select etc... message)
BUT, it will boot if I force the hard drive using F12 during the startup. (I've verified this several times)
The mystery thickens.
A bit complicated, but I hope you get the gist.
OK, the PC is booting correctly now, but I still don't know why. Maybe it managed to shut down cleanly as you suggested.
On the other hand, why would a "dirty" shutdown have an effect on what the BIOS does? - I can understand it affecting Windows startup.
And how can the BIOS settings change without my intervention?
Maybe you can enlighten me, I'm not so familiar with the low-level part of the system.
I've never seen the "dirty" shutdown affect boot order before but if I find a reason as to why I will let you know. The only time I have seen anything remotely strange is when the CMOS battery is dying but I'm not inclined to believe that is the reason you boot order is changing. I am relieved that it is booting correctly now.
This is getting wierd!
The problem came back after the Windows update yesterday but now I've narrowed down the situation:
If I restart the PC using the "Shutdown" button, everything is OK and with the correct BIOS setting.
If I restart using "Restart" in the Shutdown menu, the boot hangs and BIOS settings change, with the external drive back in the "Hard disk drive priority" list as the first choice and defined as the "First boot device".
When this happens and I power down and up again, it boots OK with the BIOS in the correct state.
If I disconnect the external drive the BIOS is OK in both restart situations.
I defined the external drive as the default Windows backup device, but could that influence the boot sequence???
By the way, as you mentioned the CMOS battery I checked it just to be sure and it shows 3.37V, so as you thought, that's not the problem.