OS X 10.6.6 Active Directory login Illustrator Print.ai is an unknown format

Well, this is the continuation of Active Directory home drives and software troubles related to it. At the moment when most members of staff and students open a new Illustrator file they get the error message:

The file "Print.ai" is an unknown format and cannot be opened.

If you click OK a couple of times it then gives you the make a new document type window, where you can select a template etc. When you click OK to this you get one more of the errors above, and after this you finally get this error:

Can't create a new illustration. The command was canceled.

Just thinking about it, I've not actually tried opening an existing Illustrator file, but I shall when I next get the chance. Interestingly, this does not happen to all Active Directory logins. I've not been able to deduct what is the difference between logins that can and can't.

I've updated to the latest version of Illustrator - 11.0.2. We used to use NHR (Network Home Relocator) which relocated the "/Library/Caches" folder, and sorted out a lot of troubles. One in particular related to illustrator showing images placed in a document. Unfortunately I can't get NHR to work on 10.6.6.

If anyone else can add to this, whether they also have this problem, or they have suggestions, all is welcome.