Please see the most recent updates in the "Where did the .com name go?" thread. Posts number 16 and 17.
As Baz says. I was getting it a lot when I had max texture settings on 4096. Reducing setting to 2048 stopped that error. My eyes could not see the difference in regular use of the sim, i.e. flying. If you just want to take screeenshots with lots of detail, then you can reset to 4096 in texture max load settings, but be prepared in high scenery areas.

NC