It boots into Safe Mode because it cannot fully load Windows. Alas, you don't know why this is occurring. Yes, you could reinstall the operating system, but this is not necessarily a cure for the computer's ills.
1) Click the option [i]Disable automatic restart on system failure[/i] while in Safe Mode.
2) Check to see if you have a [i]restore point[/i] in System Restore when the computer was working properly. If so, perform a [i]Restore[/i] operation in Safe Mode.
3) If that fixes the glitch, no further investigation may be needed.
4) If that doesn't fix the glitch, run diagnostics on the hard drive. You can download the free [i]Seatools[/i] utility from Seagate:
http://tinyurl.com/yvq99t
5) Create a bootable CD with the freeware CDBurnerXP:
http://cdburnerxp.se/
6) Follow these instructions to create a bootable CD:
http://tinyurl.com/4f3coa
7) If the hard drive checks out OK, try reinstalling Windows from the installation/recovery CD. Boot the computer with the CD in the optical drive (be sure the BIOS is configured to seek the CD-ROM first).
If your troubles persist, please post back in this thread with more information.
Rick/Portland, OR