Lines on screen

Hello,
Just recently on my desktop, and in some applications there are faint green lines on the desktop. My monitor does not have dead pixels, because when the bios starts there are no defects. I recently installed hl2, and was getting an error. On some forums it said to run msconfig>>boot.ini>>advanced>>maxmem and then set it to my amount (2048). Then I unchecked it after the install. That is the only change I have recently done on my pc. Please help it is very irritating

 

Nevermind people, =)
It stopped for some reason... no clue though.

 

Actually scratch that it came back. Is it my monitor, videocard, graphics drivers? Any ideas? Also now I noticed when I start up full screen apps (mainly games) there will initially be a bright one pixel thick line on the top and left edges, but then it goes away.

The blue line at near the top comes and goes...

I have an evga 7900gt, viewsonic va912B monitor, windows xp pro, 2 GB ram, athlon 64 x2 4200+.