Great info. Now I can help you:
System Restore will not restore your system to an unstable state. There are
two possibilities here:
1) The restore point you used was too old. Your system is continually
changing as you add/remove programs, install/remove hardware, download
software from the Internet, etc. If you restore to a date too much earlier
than the present day, you are mixing old system files into a very changed
system. This can cause big problems.
2) System Restore had nothing to do with it; there is another cause. You may
have a virus or spyware, or you may have misconfigured your system in some
way. In other words, there was a problem waiting to happen, and using System
Restore finally brought it out.
To get yourself out, always start with the conservative solutions, and then
work your way toward increasingly invasive solutions. Here is the first
thing to try:
"How to start your computer by using the Last Known Good Configuration
feature in Windows XP"
http://support.microsoft.com/default.aspx?scid=kb;en-us;307852
Ted Zieglar