1.
Restore Points. Your restore points are essentially gone. When you turn off "System Restore" and later turn on "System Restore"; all of your previous restore points are deleted.
System Restore "restore points" are missing or deleted2.
Blue Screen of Death (BSOD). If you want help resolving BSOD, that's the "subject" you should be posting. Post the "exact" error message and text that you're receiving.
This utility from NirSoft may help extract that information:
BlueScreenView v1.05 - View BSOD crash information3.
Clean Boot. You can use msconfig in "Safe Mode" to configure "clean boot" for "Normal Mode":
How to configure Windows XP to start in a "clean boot" state. If you can "clean boot" into Normal mode, you can probably isolate problem by bringing other programs/services on line one-by-one until problem reoccurs.
Be careful with "msconfig". Rumour has it, you can modify the settings to the point where you can no longer boot the operating system in any mode.
4.
System File Checker. If you can get to "Normal" mode, you may be able to run the "system file checker" command "sfc /scannow" either at a command prompt or from the "Start -> Run text box". This will check for missing or corrupt system files and attempt to replace them with fresh copies. You probably won't need a Windows XP CD to do this. Backup copies of these file are usually already on your hard drive; but you may have to modify windows registry to point to them. See and print out if possible:
System File Checker How To's, How to run it with and without a Windows CD.