I don't know if this is a problem with a sort of general solution or not, but I'll be happy to edit this to include any system specs necessary.
When I turn on my computer it tends to freeze at the BIOS screen. Curiously enough, after I hit Tab, it halts for a moment displaying the Memory Test line then "Primary Master" appears for a split second before some letters vanish from the screen. That is to say, "Primary Master" turns into " rim ry M st r" or something crazy. A number of letters disappear from the other words in such a manner simultaneously and the computer freezes at this point.
I generally have to restart several times before it goes through the BIOS normally. Even when this happens, the green Vista loading bar freezes for a minute or so at several different positions before the computer finishes booting to my desktop.