need help computer not working

i put a computer together this last spring and it is now not working most of the time. ever since i first used my new computer i have had some minor problems with it freezing which i contributed to heat problems because as long as i kept the computer cool it was much more stable. but more recently my computer is experiencing much greater failures. it has begun randomly restarting on me, which as far as i can tell doesn't seem to be due to any specific software or operating system. none of my problems do. i have it set up to dual boot win 98 and win 2000. also another problem i am having is that much of the time when my computer restarts the screen stays black. when this happens it sometimes sounds like it is loading and other times i don't think it is...i like to refer to this problem as the black screen of death. i found that if i pulled the video card out turn on the computer turned it of and reinserted the video card i could get the screen to come back. even if the screen is on my computer will sometimes freeze during the start of much of the time at the begining screen where it says the video card information. i have suspisions that the problem could lie in the mainboard or processor but i can't prove it yet. if you have any suggestions as to the problem or how to figure out what it is i would be very much appreciative. i will leave a list of the compontents i have...

bought through ESC Technologies...which means they test an make sure every thing is rated to be used with each other, but isn't always fullproof.

CA700-atx midtower case with 300 watt power supply
2 FANA0- fan for athlon socket A processor
1 YY60FANS-Dynaeon Industrial Co. 60 mm fan
1 YY80FANS-80mm fans used in YY cases
1 AMD-A0800A -AMD athlon 800 MHz (PGA) tray processor
1 FICAZ11-motherboard; ATX for socket A
1 TEACFLOP- Teac floppy drive, 3.5 inch, 1.44mb ivory

other compontet either bought through other vendors or salvaged from an older comp most of which i don't have the exact spec for at this time

hercules geforce 2 gts 64MB w/svideo and dvi outputs included

dvd rom drive
zip drive
30 GB HD
sound card (older model i think a soundblaster of some sorts) from my old computer
NIC ethernet card
1 256mb kinsington pc133 ram
1 128mb kinsington pc133 ram

since i don't have my comp sitting in front of me here that is all i can think of or have record of at this time. if more information is desired just let me know i would be glad to provide it if it will help get my computer running again. thank you all whome take the time to read this and help me out with any suggestions.

if that all don't work - I rekon you could have a faulty mobo, see if you can get that checked.

You are responsible for any damage the info in your post may cause to my system.

Why did you do that?

You are responsible for any damage the info in your post may cause to my system.

You are responsible for any damage the info in your post may cause to my system.