T400 Screen Flicker Issue

[Performa636CD]

I have a Lenovo T400 which is having screen issues. A few months ago, after resuming from sleep mode, the entire screen would flicker ever few seconds. It made the laptop just barely usable. I ignored the problem by just not going into sleep mode (although switching screen frequency between 50 and 60 Hz seemed to fix a screen flicker temporarily). Now, a bottom ribbon of the screen flickers and does so continuously. However, it's only the bottom 50 pixels or so such that by adjusting my resolution from 1200 x 800 to 1200 x 768, I don't lose any screen space to the flicker, although the flicker is still there. The "flicker ribbon" is basically the width of my taskbar and runs the entire bottom length of the screen. Does anyone have any idea as to what's causing this? The "flicker ribbon" was initially only a few pixels wide, but is now 30-50 pixels wide. The only think I can think of is maybe running a video game that pushed my computer is damaging the GPU? Any thoughts or advice would be appreciated.

I'm running Vista Business 32 bit (SP 1) with 2 GB RAM and a T9400 CPU. My GPU is an ATI Mobility Radeon HD 3400 series with 256 MB.

EDIT: I swear, IMMEDIATELY after making this post, the "flicker ribbon" reduced from 30-50 pixels to 1 or 2 pixels wide (the way it used to be). My ThinkPad has gremlins?