Screen goes white

[RussianBear]

I'm sorry if a similar question has been posted and I can't find it. Lately the performance of my machine has really deteriorated. I have a Dell that is about 2 years old. I've decided I need more RAM (I'm waiting on my damn check from UB to buy it). For about two weeks now I've been having a strange problem, the screen just goes white. Usually it happens instead of the screen saver being activated, but more recently it can happen while surfing the web too. And, it has been taking longer and longer for the screen to return to normal. The last couple of times I had to turn the computer off. Is this a RAM issue or maybe a monitor issue? Anyone here have a similar problem and, if so, what was done to resolve it?
Thanks 2+2.
Bear