Hello Steven, hello beeing good,
thanks for the rainmeter skin ini.file and your help. Yes, I'm using the absolute latest MB and Rainmeter beta versions. Unfortunately that does not do the trick. In the meanhwile I figured that my MB even does not load up CD Art Dsiplay anymore, allthough it used to do this, before I decided to skip CDA some months ago.
Anyhow, I assume this is a MB problem, since I've justed tested this on a Windows 7 computer, where there only was Rainmeter installed. So I installed MB freshly there and it it worked like a charme from the getgo.

Got back to my computer, de-installed MB as well as all settings in C:\Users\Userx\Music\MusicBee and C:\Users\Userx\AppData\Roaming\MusicBee
and re-installed MB so I thought I'm nearly on a fresh install, but neither Rainmeter, nor CD Art Display are working. I guess there must be some more registry settings e.t.c. which can cause the problem, but I'll give up at this stage because it is getting deep and ugly now and I do not expect anyone to follow and help, since it really might be an install/update error on my machine here. MB is the best Music Player around, no matter what.
Thank you!