I've been using Xpress Pro for 2 years with Mojo and have notice picture imperfections on footage shot over 100IRE. The imperfections occur on very high contrast images. Small lines (inverted equal signs) blink on and off very fast. Bringing the video levels down with color correction does not fix the problem. I can digitize the footage into Final Cut without any imperfections. In fact, I can fix this problem by digitizing in Final cut....bring the levels down to 100ire...and redigitze to Xpress. Also, I've noticed another problem with video levels over 100ire. I capture footage shot over 100IRE in the Avid and when I do a digital cut the video levels are clipped at 100ire. This happens on our windows Xpress Pro 5.1 and Mac Xpress Pro 5.4. Both have Mojos. Footage is shot on DVCAM. Digitized via firewire with a Sony DSR45 deck. Thanks, Patrick Miller

 One of the tools in color correction is "high clip" under the controls tab.  This is designed to clip any part of the signal that goes higher than 100 IRE.  100 IRE is the official legal limit for white levels. Anything higher than 100 IRE will be grounds for rejection by a Broadcast QC inspector. You never want your white levels higher than 100.  However, that being said, you can "cheat the reaper" on overly dark shots with brilliant highlights by pushing levels well above 100 IRE and then using the high clip to flatten out the waveform at 100. 

I'm not quite sure what type of issue this is causing you, since this is keeping you legal.  Do you have a specific problem that needs to be remedied?

{EDIT} If your source material was recorded with over-driven white levels beyond 100 IRE, you would need to capture that material with an anolog signal instead of firewire, so that you could lower the video level before capture.  But, just like slightly overmodulated audio, over-exposed video cannot be undone, it can only be slighly adjusted and controlled.