Yesterday, my computer worked perfectly. However, as of today I get a very peculiar situation. The startup seems to work well until I access my desktop, where the computer inexplicably freezes after one or two clicks and everything becomes unclickable. Sometimes, the screen turns white. During the freeze, I am still able to move my mouse around, but absolutely nothing responds past that, including my fervent attempts of using ctrl+alt+delete. When I use safe mode, the computer works well. So far, I have used a disk cleanup, defragment, and spyware search and destroy without any change. I have rebooted multiple times. Please help?