To Diagnose Freezes (2 Instances)?

I've been living with random Vista freezes for about 6 months - they are frequent but no more or less so over the months - and they began after I clean installed a Vista Ultimate on a new PC (specs above). The freezes can occur at booting, at the Welcome screen, opening Windows Mail, opening either MS or Firefox browser, during a running video - just about any time doing anything. Oh, and sometimes I get a random reboot for no apparent reason but that happens much less often. Device Manager is no help - usually reporting that the event was "unexpected." How profound!Other symptoms, when rebooting after a freeze, indicate - often as not - that my bios settings have been reset - & a booting screen asks me to choose (1) to reset the bios to default values automatically or (2) to enter and manually reset them. Normally, in the bios.

I manually choose to disable the floppy drive & set booting sequence to A. CD B. Hard drive C. third option requires "disabled' for the latter sequence.So, often as not, after a freeze, I find that my floppy drive and boot sequence settings were reset to the defaults - changing my preferred settings. I use Device Manager to 'disable' two card reader icons and a floppy controller - so the icons show an downward arrow to reflect the settings. Why? Because my new PC came with an internal, defective USB floppy/card reader installed, and, yes, I did try to remove the unit but the desktop tower is very poorly designed & I am not able to access and remove the defective floppy's connection to the motherboar............