Hi:
There are threads on this on the forum somewhere. I do not know exactly what component it is that causes the problem but this as an overheating issue that is a result of poor design. There have been several attempts (I think) to remedy this by putting heatsinks on the offending part or parts. However I do not think that these have been very successful. There is a lot of trial and error involved in sorting these out and it is apparently not a very rewarding experience.
If I had one (and I don't), I would be tempted to gutt the system and put the internals of a Panasonic or something in the case and suffer the fact that you loose BEO4 control. At least it will look nice, and will work!