Chrome's "Default" user directory locked

Chrome would not start. I spotted the problem down to the following situation:

The following folder C:UsersUserAppDataLocalGoogleChromeUser Data is locked - always. Also when chrome is not ruing. Also immediately after a reboot.

Furthermore, I tried to unlock it with both the "unlocker" and "lockhunter" applications. Both applications claim that the folder is not locked, however, when asking them to rename it they fail.