I have also found that this event occurs when I open more than one pdf document.
I have also tried the following setting with the video card:
- changing to a lower resolution
- changing to a lower refresh rate (from 70Hz to 60 Hz)
- lowering AGP speed from 8 times to 4
None of these setting reduced or remove the speckles.
I have also very recently (the past few days) reformat my computer.
I also remember encountering this problem on a newer Dell desktop(business grade) in a computer lab.
Both computers are running Windows XP OS.
Try turning off video acceleration.
Thanks for the reply.
I discovered that it was a hardware problem. Video card is dying/overheating and won't render vector objects.