Computer Mystery Problem For Pro's?

I'm usealy one to be answering questions about computers but every now and then one must face the cold hard facts and that is i dont know it all :)

I am useing Windows Vista and it has'nt been a picnic strugleing with this os but i had it running good untill a few nights ago. My mouse froze to the screen and no matter what i done rebooting etc. the mouse would'nt move so i throught my optical mouse may be shot but i have an extra optical mouse so i tried that and it did'nt help.

I have been doing all the right things like regular computer maintaince,disc clean up,Defrag,msconfig,disc check and i updated and ran my antivirus and spyware programs daily.

Out of desperation i reinstaled Vista i opted to keep the old partishion and got the message that Vista would install over the curent folder Vista and would create an old folder named "old version of windows" and also said some of the old programs may not work any longer.

The reinstall went perfect and befor i knew it all my hardware like my printer etc were updateing the drivers and Vista was updateing so i was impressed at how well things went.

My computer was running like new again the reboots were fast aswell as the shut down so i throught i had it made.

Two days later i hear strange sounds comeing from my speakers like when your playing a game or something the sound's dont last but a few seconds then there gone for awhile. The only window i had open was Yahoo and then the bad part happens again my mouse freezes to the screen WTF? i can sometimes jiggel the mouse and it free's up but most of the time i have to reboot to get everything working for awhile. I checked my boot record and it's full of Critical events and warnings so i realy dont know what this all means except it is'nt good. I have come to the conclusion that it must be a problem with the mother board or the hard drive.