Troble mounting ZIP, CD + Disk Images


:confused: Since a few weeks i can't mount any disk image, ZIP, or CD's without getting trouble. After restarting the finder the image is sometimes mounted, but when i try to dismount that image again my G4/450 freezes. i can not even kill the task with the force quit )-:
So is there someone who can help?

Here is what i already tried:
disk doctor OK
reboot in single user mode and fsck -y
no problems were found )-:

Need help

Thx Markus