...he definitely cannot confirm that there is "not that difference" according to his experience with Samsung Android 4.0.4 compared to CM9 and so I think there is a lot of difference between JB delivered by Google and (not yet available) JB by Samsung. ...
So maybe it is indeedly an incompatibility between CM10 and the driver for Windows XP OS as I cannot connect to two different XP-machines but to Mac and Vista.
But you are right, this becomes off-topic, I stop it. Thank you anyway for the hints.
edit:To bring this to a point, I have to tell that I switched back to 2.3.5 after about a week.
CyanogenMod 10 (4.1.1) is yet not very stable and it was a big error of mine not to read enough about it and just installing it. I had to read later much more ;-)
What I said before, that there is no reason to change a perfect running system (OS 2.3.5) with a new and not totally compatible system was exactly right. I was too curious and this was a mistake.
Your son was very right as well, saying that CyanogenMod 10 (4.1.1) is not the same as the stock ROM.
Not at all!
I know it now and I had to pay this knowledge with many hours of struggle with the buggy OS.
Blame on Samsung not giving their sources.
Maybe I will update when the JellyBean stock ROM for SGS2 is available (with root).
At least locus did work flawlessly on CM 10 :-)