After installing SP2 on Vista 32-bit HP laptop, all browsers (Firefox, IE, Maxthon) periodically freeze randomly. It occurs when opening a new webpage. It might happen after 45 minutes of browsing, or 3 minutes. The only way to get out of it is to right click the taskbar, "end program", and say "close now" when it tries to search for a solution. Or occasionally, I have to hard reboot. It doesn't seem to correlate with any one particular type of webpage, but I'm assuming that something being loaded doesn't play well with my system.
I would uninstall SP2, but it fixed several even more annoying system problems I'd had with my computer.