Safari Horizontal line when scrolling down

[MagnumJoe]

I have a Macbook Pro 2.4 GHz Penryn. When using Safari and scrolling down pages I see a horizontal line. This only happens in Safari, Firefox works fine. I've tried resetting Safari but I still see the line while scrolling. Any help would be appreciated.

 

[mhnajjar]

I am having the same issue in Safari and FF 3.0 while FF 2.0 used to be fine It is happening in my iMac and it is driving me crazy!