Hi Jim,
It occurs to me that there is probably a generic reason why more AV programs are causing more problems in MC.
I think it is because when MC is playing a track, it is very often transcoding the original file on the fly to another format, and this other format is buffered to a temporary file on disk. Obviously this temporary file is totally new to the PC and as far as the AV is concerned it appeared from nowhere and has no established trust credentials.
When you think about it like that, it seems only natural that an AV application would have heuristics to give special attention to just such types of files.
Perhaps one way to avoid undue attention from AV applications could be to not write such temporary transcoded files onto disk, but keep them instead in RAM. Obviously for really big transcodes you might run out of RAM, but maybe you can do something using Windows paged RAM management system. (At least in that case you would as it were have Microsoft on your side in any discussions with AV vendors...)
EDIT: Another idea could be to apply a Digital Signature to your temporary transcode files using a JRiver signing certificate issued by a globally well known certificate authority (e.g. such as VeriSign). However this might not be possible since you cannot apply a meaningful DSig to a file until after it has been fully written to disk (i.e. until after its contents have become stable).
EDIT 2): We have also recently heard about malware being spread in bogus MP3s so perhaps another way to avoid undue AV attention is to store your temp files using a file extension that is explicitly non executable and explicitly not able to run macros; suggestions would be .tmp or even .txt -- however this might be just too obvious a ploy that any serious AV application would try not to be duped by...
