Jim,
This definitley sounds like a system crash to me. If some of the driver files are corrupt, then it would prevent a complete boot from taking place.
What you can try if you get if booted up, is to run a Diskscan and Defrag.
If you have the Windows Recovery Disk, then you can do a partial reformat of the Windows drive without touching additional drives.
A "partial reformat" acts like a repair not a replace.
Remember that if you reformat the primary partition, you must make it the system drive with the coding X: format C: /s where X is the prompt and C represents the primary hard drive.
Hope this helps.
techie