I think its probably going to be a memory problem.
Do you know if you have more than one stick of ram in ?
If you have 2 sticks in then take one out and see if it will boot ok each time.
If its still doing the same then put that stick back and remove the other.
If you only have a single stick then you need to run a memory checking program such as memtest86 from :
www.memtest.orgYou want either :
Download - Pre-Compiled EXE file for USB Key (Pure DOS)
Download - Pre-Compiled package for Floppy (DOS - Win)
From the section ** Memtest86+ V1.70 (01/14/2007) **
If your PC has a floppy drive, some pcs foolishly dont have floppy drives these days, then extract the file from the package for floppy and run it on your pc and it will make a bootable floppy for you.
If your pc doesnt have a floppy and you have a USB flash drive then use the USB option.
Whichever option you choose then set the bios to boot from that device first and let it boot the pc and it will run the diagnostic check, it can take some time to thoroughly test the ram and its usually better if you have multiple sticks of ram in to run it with single sticks at a time in the pc.