Thorte,
For those of you having this issue.
Please try the following.
If you create a new user on your computer, does iTunes stop responding when you connect the iPod or iPhone when logged in to a new user? Please make sure you logout of the original user first instead of switching users.
If it is fine in the new user, try creating a new library in the original user account on your computer. The steps are in this article:
http://support.apple.com/kb/HT1589
If it works with a new library, it could be the iTunes Library.itl file needs to be rebuilt. Switch back to your original library following the steps in the above link, and then try this:
http://support.apple.com/kb/HT1451
Hope this helps,
Nathan C.