Restart -- WONT on XP pc

[mrlewp]

I've searched, but all I find is problems with rebooting, starting up, etc. My specific problem is that the "RESTART" option fails......... to reboot the pc. No problem shutting down , booting from OFF state, or hibernating. It just will not do a Restart!
One time, a program installation did make it restart , forget which one. Even M'soft updates requiring restart will not force it to . I simply power it up soon as I need it again.
Any thoughts?

 

[KSoD]

Have you tried a restore point to a time it worked? Have you tried a repair install?

 

[mrlewp]

Have not tried Restore Point, without knowing just when problem began. Would rather not, unless this "annoyance" cant be cured, as I've done a lot of trial installs lately, followed by clean removals. Restores always add lot's of junk files that you have to re-discover.
A Repair ? Explain, please.