Vista and Remote Web Workplace

Hello,

I have a number of clients that use Remote Web Workplace for remote users to
access computers in their office. This has been working fine for a long
time. Now some remote users have bought new computers with Vista Business
Edition. Everything in the RWW still works except for when they enable files
to be transferred between the remote computer and their local Vista machine.
When they try to connect they get a Javascript error on the page;

Line: 323
Char: 4
Error: Permission denied
Code: 0
URL:
https://server.domain.com/Remote/tsw...edirectaudio=0

I have made the server, and domain info generic but the rest is exact
message. If any of the other options are selected without the transferring
files option everything works fine. Has anyone else had this issue and been
able to solve it?

Thanks

John