It may well be some malware causing you problems
To regain control for Task Manager and Regedit etc have a look here
http://www.raymond.cc/blog/
About the 6th item offers a tool that will regain control of what the grubs turn off
Naturally these places come with the caveat of DO SO AT YOUR OWN RISk..no guarantees but it has never hurt me
You have to be able to get control of your system first
For the one that is rebooting try going to SAFE MODE...tap the F8 key as soon as the first white writing appears on the black background....you should get a number of offers including LAST KNOWN GOOD BOOT and SAFE MODE among others.
You need to get there and have control before any tools will be useful
ONCE YOU FIX IT GET SOME PROTECTION...LOTS OF GOOD FREE STUFF THERE WAITING TO BE USED
Good Luck
Baudy!