I think i had this problem.
During the restarting process, do you see a blue screen with writing on it flash for about half a second at any time??
If you do, you need to 'disable restart after boot up failure' - (its called something along the line of that).
To do this you need to press one of F keys, which will take you to the 'Advanced menu options' -(its called something along the line of that).
During start up, you will be shown what keys to press, (this will be a normal screen just as if your pc would be working) - And as far as i can remember its F12.
When you get to the options where 'disable restart after boot up failure' will be, and once selected that, it will basically stop restating and stop at the blue screen where the error codes and stuff will be displayed and then further investgation can be taken place.
Any questions just ask.
Oh and before you try that, have you tried removing what ever you recently installed through safe mode??