I found that shellex was not specific enough to figure out the problem. After disabling every single non microsoft entry there was no improvement.
I found a better way of figuring out my problem. I downloaded WhatIsHang(also made by shellex) and i fired this up while my context menu was hanging.
It showed that it was picasa3 which is not installed on my pc anymore was causing the hang. I fixed the problem by installing picasa3 again and then uninstalling it. now my context menu works again.
Thanks for the excellent feedback, holymoses. WhatIsHang is already on my checklist... hope I can write some troubleshooting guide so that it helps users.