I have a recurring problem.
The screen is often flooded with thin vertical blue and white lines (like pinstripes) that distort all light areas of the screen or pictures.
It will sometimes stop for a while, but always returns. It infected my desktop for a time after I transferred pictures to it, but it "cured" itself in a short time.
When scanned with AVG the following results always occur under viruses:
A scan sometimes stops the problem for a time, but it soon returns. Restarting may also stop it for a short while.
I previously used Norton and it never detected anything.
None of the local guys have ever seen or heard of this.