BIOS screen disappeared...?

First, my P4 2.6 mHz computer started rebooting in the middle of a bootup.
It would take four or five tries to get through the boot process and into
Win2000. I also noticed that often when I started it up, the computer would
run chkdsk on one or two of the partitions, but never the bootup partition
(C. It never found anything wrong with the files, just kept checking.

I started running some hard drive diagnostic software, including Norton Disk
Doctor, WD Data Lifeguard, Partition Doctor, but never found anything wrong,
including on surface tests. I also ran Memtest86 but didn't find any
errors.

Then I noticed that the BIOS startup screen was no longer there, although
there is a point where I can hit F8 and get a choice of Safe Mode bootups.
Currently, the computer seems to be working ok, but no sign of the BIOS
startup screen. I'm not sure what this means, but I'd like to have it back.
Any suggestions for troubleshooting this?

John