So I was getting this odd graphics glitch in Second Life. Gray boxes appearing in textures now and again. Here's a pic showing it.
It wasn't happening on other systems, just my main one. I'm on a Windows XP box, so I tried the usual uninstalling and reinstalling to no avail. Updated grapics drivers too.
Turns out it was happening because I have an overly fancy ATI graphics card. It and Second Life were both trying to pretty up the screen, and they were tripping over one another.
Here's what fixed it.
Catalyst Control Center, Graphics Settings, 3D, All Settings:
Set Catalyst AI to Standard,
Set Adaptive Anti-Aliasing to Performance.