Reinstall the programs properly and check the user permissions on the Library folder. It simply can't access it.
I changed the permissions for the folder & file and everything is working great!
I have the exact same problem as rumtone had. The only difference is that once I uninstalled After Effects CS5.5 and reinstalled it, and checked the user permissions on the Library folder it still gave me the same error message. The error message only occurs when I try to save or when I try to open save files. Is there anything else i can do?