Sorry I don't know the solution, but it's a well know issue since the beginning. The strange is that in that according to the newest 2.0.4 firmware changelog it should have been fixed by now. Some reported as they didn't experienced the resolution reset since they installed 2.0.4, but others did and still have this problem, just like before. It seams that it's not have been 100%-ly fixed and it can occur in some circumstances.
Maybe it has to do something with the AVR configurations or type, or maybe even the colourspace settings and switchings could affect that. Hope Futeko will report it to HiMedia, and would be also nice, to at least we could have some feedback from HiMedia from the -possible- causes of this long lasting issue.
Futeko?!