Screen saver stopped working

[ouizee47]

Okay, I'm not a computer guru, but do know a "little" bit about it...just little enough to get me into trouble fast! Back in June I dropped the computer off with the guy who'd made it, to have him install a new modem. For several months before that, the screen saver had stopped working. I could get it to work manually, but sometimes something would happen to jiggle or vibrate the computer, and the screen saver would go off again. Being lazy, and due to having a really hard time getting down in the floor, under the desk (it's a virtual cave down there because it's so dark!), I put off hooking the desktop back up until tonight (been using the laptop). Ok, got it hooked up and running, and noticed the screen saver did not work. Soo, thought maybe it was the Avast a/v proggie...something not jiving with the screen saver (don't ask...don't remember why I thought that lol). So tonight I unloaded it, and installed avg instead. Well, it STILL won't let the screen saver to come on...any screensaver..not just one or two...even the one that comes with the puter won't come on automatically. Help? Ok, I've rambled long enough and I'm sure I've confuzled everyone by now. Thanks in advance for any help you can give me (btw, the screen saver on the laptop is the same as the one I'm using on here...and it works fine!).
ouizee