Cannot authorize my mac and all iphone apps will be deleted!

Question

As I sync my iphone to my mac, at the end of the syncing process, I get the message:
(My OS is in Swedish, so these are my own translations into English.)
"This mac is no longer authorized for apps installed on the iphone device. Do you want to autorize this mac for objects purchased from the iTunes store? If you do not authorize your mac 101 apps and their data will be deleted from this iPhone."
As I try to authorize it (Yes, with the correct account name and password) it just says:
"An error occured when authentication information was saved on this mac.
The required file was not found or has a permissions error. Fix the problem and try again, or deauthorize if the permissinons cannot be changed."
As I searched apple support I read somewhere that syncing required the shared file. I showed that file´s info and set my (I´m an administrator) rights to reading and writing. It did not help.
I then ran the Disk Utilities application to fix my permisssions. It did not work.
I then tried to shut down iTunes, I could not even close it.
I tried to deauthorize my mac, but I just got the same error message as above.
I know I have had problems before with permissions in different applications, but they have always been solved by just changing the permissions in the "show info" of the file.
I would love to just make a full system restore, but I´ve got almost 1TB of stuff on my hd, and it would just take forever...
What do I do?
Please help! I´m desperate! Thanks!
Message was edited by: genzaigirl

Answer 1

Your iPod can only be synced with one iTunes library at a time. If you try to sync the iPod with a new computer, everything that is currently on the iPod will replaced with the contents from the new library.
If you do not wish to lose your Apps, you can use the File -> Transfer Purchases option to move them over to the new PC.
B-rock