taking ownership itself doesn't do harm to my OS,
the extra changes with registry are already removed,
reverting troubleshoot program doens't work at all since it couldn't provide any solution at all
reverting fixit from microsoft doesn't work at all since it also couldn't provide any equitable solution.
reinstalling the driver shouldn't rly do anything bad at all, since I didn't change any graphiccards
trying stuff in the windows personalization settings was the first thing I've done, repeating something a 4th time won't help I guess.
EDIT for SOLUTION http://djabytown.deviantart.com/art/...lack-143467965
I've just applied this theme and I got back my transparency, explorer.exe etc got replaced (backupped the old files)
and yeah it looks great now

even the taskbar got it's transparency back
how did I replace those system files?
I've used a linux live cd (fedora 15 to be accurate)