laptop monitor troubles (or "if in doubt, bang it")

[arcadian_girl]

for the last week or so i've been having trouble with my laptop monitor. i have a Sony Vaio pcg-grz660. i got it around 2002 or so and it's basically hung in there pretty good-it's pretty tough (i'm not easy on things :/ ), but in the last week or so the monitor starts to do that thing-you know on a tv when the horizontal hold goes out and it starts to look like the pictures running down the screen over and over? well it looks like that, except the screen goes gray. it seems to happen especially when i'm scrolling, or using something that takes a lot of RAM. its gotten worse over the past day, to the point where it starts doing it and then it reboots itself. the last few times it did it, it did the gray flippy thing and then went black. scurry-i thought it had died. so...at one point this morning i really thought it was done, and i was really frustrated, so i banged it hard three times on the bottom and three times on each side-ever since then *knock on wood*, it's been working fine.

my question-has anyone ever heard of this happening and know what's causing it?

thanks.