Definitely sounds like a hardware problem Raul.
Are you getting a post screen or nothing at all?
If you can boot into safe mode as Karlsnooks suggests then try doing a system restore.
Alternatively, if you have a Windows 7 disk or a rescue disk try booting from that and do a repair install.
Regarding PSI Secunia, I tried on a x64 Windows 7 install and found it immensely annoying.
Every time I logged on it would bombard me with reminders to update Adobe Flash and Adobe Reader. I'd do that and then it would remind me again. I began to believe that Adobe products are constantly out of date.(surely not
I take your point about being useful in keeping everything up to date but it got so irritating I had to take it off.