Delete the preference file. It is probably corrupt.
I had already deleted the preference-file, but still the same error.
There is another problem-report (http://forums.adobe.com/message/1771582#1771582), describing the same problem together with printing-problems.
It turns out, that the filesystem on my internal hard drive (which is formatted case sensitive), is the troublemaker, as described in the 1771582 report, because I also can not install Adobe Photoshop CS3 on this iMac (wrong file system).
It's strange, but ADOBE does not seem to support case sensitive formatted Mac OSX hard-drives, this causing trouble with Adobe Reader and Photoshop CS3 Install.
I will re-format the Internal hard-drive (with no case sensitive) later and let you know the result
Problem is solved.
I have reformatted the HD without Case sensitive!! , and after a restore its working now.
So. ADOBE does not support any Case sensitive HD, thats strange !
The problem persists.
It is occuring in MAC OS 10.5.7 English as well. Yes, I do have the 'case sensitive' HD as well.
This is a major oversight--and if it is the case, a prominent and large warning would be advisable.