Quickbooks 2002 slow on Windows 2003 Small Business Server R2

Have QuickBooks 2002 Premium running on 5 workstations sharing the same data file.  Network was peer-to-peer where one of the workstations acted as the server sitting in the corner and that is where the QuickBooks data file resided.  Everything worked great.

Now a Windows 2003 Small Business Server R2 w/ISA Server 2004 has been put in place and all workstations are connected to the domain and have the ISA client installed and configured.  The QuickBooks data file is now on the Server in a shared folder that ALL users have full permission to and are mapped via a drive letter.  QuickBooks is really slow when doing some tasks initially.  For example generating an invoice can take up to 4 minutes to load but looking at the customer list is fast, takes seconds.  After you get through the areas that are slower once they are fast after that until you close QuickBooks and reopen it.

What I have done to try and resolve the speed problem is:

1.        Turned off indexing on the folder holding the QuickBooks data file on the Server.

2.        Symantec Server/Workstation Anti-Virus 10.2 Business Pack on server excluded scanning folder holding the QuickBooks data file.

3.        Symantec Anti-Virus 10.2 client on all workstations excluded scanning folder holding the QuickBooks data file AND the c:\program files\intuit where QuickBooks is installed.

4.        Verified and rebuilt QuickBooks data file.

5.        Server reboot after all changes.

Still have same problems, some QuickBooks tasks are initially very slow.

After more testing it appears if you log into the QuickBooks data file with a QuickBooks login that DOES NOT have ADMIN rights speed is fine for all QuickBooks functions.  ADD an admin user, the access to the QB file slows the other users.  Not sure how and why QuickBooks user rights have anything to do with the Server and simply accessing a data file.

Anybody else experiencing this problem with any version of QuickBooks?

Regards,
Torrey