iTunes could not back up the iPhone?

[daaneel]

Whenever I try to sync my iPhone 4 running on iOS5 I get this error during the "Backup" part of the sync

Why?

 

[PNutts]

Without more information it looks like you don't have permissions to write to the backup location or there isn't room on the disk.

 

[daaneel]

Wirelessly posted (Mozilla/5.0 (iPhone; CPU iPhone OS 5_0 like Mac OS X) AppleWebKit/534.46 (KHTML, like Gecko) Version/5.1 Mobile/9A334 Safari/7534.48.3)

How do I check this? I am logged in to the administrator account on my computer.