In general, there have been reports of video artifacting and inexplicable text behavior when the IMS Twin turbo Acceleration is active.
There is not a confirmed known issue at this point. However, the problem is reproducible, and has been forwarded by Anthony Snyder to IMS for resolution.
The only workaround, at this time, is to turn off the Twin Turbo Acceleration.
Machines Affected: PowerCenter, PowerTower, PowerTower Pro, PowerWave