It's a Pavillion, dv2500, Intel core 2 1.5ghz 4 gb, 32bit OS, W. Vista SP2. (It has ubuntu in another partition, but ubuntu is wirking pretty fine).
The computer keeps reboting after some minutes while it tries to load the system. Safe boot is working normally. I've already tried system restore during a 'safe mode boot', but this works just for the first boot, and than in the following boot it begins to reboot automatically againg.
Avast and Malwarebytes logs are clean.
Thank you for your help,