Hi Peke,
thanks for your quick answer. I've done some testing tonight and found out, what the problem is. It's not MM
I ripped my WAV files with Easy CD-DA Extractor. There's a feature called "Enable Metadata". It means, that the WAV files will be tagged after ripping.
And that's the problem. I think CD-DA tag the files in a different way than MM does. If i load such a file in MM, i see no tags (If i load it in Hex Editor, is see that some kind of tags are present).
Because MM (and my uPNP Server) saw no tags, i've used MM to tag it. And this is the point, the problems began... The file now is "double tagged". MM is not aware, that the file contains tags and appends the tags to the file.
If you load such a file in MM, no tags are shown. And, taataaaa, you think. Hmmm no tags, let's tag again

The result: Three sets of tags on the end of the file (and so on, and so on).
Finally i take such a "mulit-tagged" file, convert it from WAV to WAV (but without the "Metadata" feature) and tagged in in MM. Bingooo.
I'm not really happy, 'cause now i have to convert (or rip) 4000 files again.
I assume, the root cause is, that CD-DA did not tag in the right way, so MM comes in trouble...
If you want reproduce the problem:
Download CD-DA from
http://www.poikosoft.com/
Rip or convert a file to WAV format (Check "Enable Metadata" on the bottom)
Load it in MM and tag it -> Tags are displayed
Load it again in MM -> No tags are displayed
Thanks for your support and sorry for my bad english...
Bye
Myrrdin