Posted 20 November 2009 - 04:23 PM
How about if you boot from a CD? (or DVD)
If it can boot to a CD, it could very well be your hard drive. If you can boot to a DOS prompt from a CD, see if you can access the C: drive and run CHKDSK /F, that should tell you some info.
If you know what brand of drive it is, the manufacturers website can sometimes have an available diagnostic.
Before you do any of that, try reseating the RAM. Open it up, take them out and put them back in.