As of January 25th, 2011, it has become apparent to the majority of the user base on AVS that Denon has addressed and remedied BOTH the "Blue Rain" and "Audio Loss" "bugs", via a pair of firmware updates to the unit.
So long as properly updated, NO 4311's should suffer from either.
Please ensure your unit has the most recent firmware. You can do this by connecting the unit to the internet via an ethernet connection and checking for a "firmware update" within the on-screen menu, found within "network settings".
See the official 4311/100 thread for further discussion regarding the units:http://www.avsforum.com/avs-vb/showthread.php?t=1274153
This poll is purely an effort to get a handle on just how wide-spread the video-related "blue-rain" and audio loss (not to be confused with temporary audio drop-outs which are not terribly uncommon amongst Denon ((and other)) AVR's...especially with cable and SAT receivers) troubles are, as well as provide a clearing-house for information specific to either of these unfotunate phenomenon with this otherwise excellent AVR.
I invite me fellow AVSer's (especially those actually experiencing either condition) to supply those unsure of the make-up of either with a helpful, brief, testimony if they're so inclined.
In an effort to narrow the scope as best we can, it would also be helpful to include the following: serial number of your 4311/100, display model, methodology of connection, source components (and whether they are specifically effected), etc.
Perhaps a baseline of when, where, and how these bad guys are occurring will yield some assistance in finding a solution.