Upgrade in Vista Business.

I have a full copy of the Vista Business Upgrade DVD which is giving me problems both with Parallels and VMFusion (I have licensed copies of both).
I have spent the last few days trying every situation, but the end result is the same.
The Parallels approach:
First I installed Vista Business (upgrade DVD) under a VM session - but didn't activate it, as its an upgrade copy I own (Microsoft actually told me you can do this, and it works!), once the install has completed, you get 3 days to register/activate it, so what you do then is run the upgrade DVD on top of the installed/unactivated Vista and do an upgrade. You can not use the Upgrade Key on the first install as Vista detects its not upgraded and says the key is invalid, but when you upgrade itself <lol> it works fine! Once the upgrade has completed, all is fine, and you can activate it with the product key. However when I try and access My Computer under VM, the shared files/folders are not accessible, if you try and double click the shortcuts on the desktop you get an error stating these folders are inaccessible/invalid. (they worked fine before the upgrade).
The VMFusion approach:
The same problems occur as above, however I have also tried XP and SP2 then upgrading to Vista Business.
My Mac is a 27inch IMac.

Any suggestions or thoughts as to why this happens?
Chris