Sorry about that. Specifics:
Adobe Premiere Pro CS6 6.0.5
Recent updates installed
Windows 7 Pro Service Pack 1
Intel Core 3.40 Ghz. 32 GB RAM
Source footage is a variety, from P2 to exported .mov animation files from After Effects. Does't seem to matter.
No errors, and it was noticed about 3 weeks ago for the first time.
No third party effects or codecs,
Not using Mercury Placback
Problem occurs during preview and export, Media Encoder, After Effects, and Premiere Pro.
The only thing I can think of is to update your video driver.