BleepingComputer.com: vista won't boot

I put the 'System Mechanic'disk in the D drive, but didn't insert it. I had to finish something online, and did so, but then got an automatic restart! The D drive went in, and the system tried to reboot, but wouldn't. Gets to message "Press DEL to run Setup, Press TAB to display BIOS POST Message. "
No change while I:
1) restarted
2) tried to restart using original WIN VISTA 64 OS Disk that came with the custom system.
3) tried downloaded boot disk from winimage
4. called, emailed and prayed to Microsoft, but no answer or contact
Only thing I found online for somehting that might have been similar was a suggestion to remove the CMOS battery, wait 3 minutes, and restart.

Next????

What message did you get when you tried to restart with the Windows DVD?

I get the same message when I try to restart, no matter what disk I use, whether a bootdisk, the original vist64 os disk that I installed about 8 months ago. I've restarted many times, trying the DEL, TAB, F8,F2, etc. Tried holding key down as well as tapping the key when it starts to boot. Short time, <5 sec. between time power on and message is displayed. The only other thing that comes up is the monitor logo as the first image.

I'd suspect one of three things:
- boot stuff messed up in BCD (run Startup Repair to fix)
- problems with the hard drive (run a diagnostic and run chkdsk /re)
- BIOS issues (try resetting BIOS to defaults).

How do I get into BIOS. Startup only gives the same message as above re: DEL or TAB action. What happens if I pull the SMOS battery and put it back after 3 minutes?

"Press Del to run setup" - that should get you into your BIOS.

ok, it's fixed. As suggested, I removed and reseated the four RAM cards, and it rebooted perfectly. Thanks, all, for your input.