Over the past few days, this is what has been happening: I turn on the laptop, the Dell logo comes on, then the welcome screen comes on and the desktop loads. At this point, I can use the laptop. But while I'm in the midst of doing something (or even when I'm not doing anything), the screen goes black for a second, then the desktop loads again. Then another black screen or two pops up before the desktop loads properly. This hasn't affected performance - all programs work fine and there haven't been any freeze-ups.
At first I thought the problem might be due to McAfee, so I removed it using the removal tool on the McAfee website. The problem still persists. I haven't installed anything new except Firefox, KMPlayer, Pidgin, 7-zip and MediaMonkey.