There is an excellent Blog here for troubleshooting Remote Web Workplace within Microsoft Small Business Server 2008.
I experienced an error (50331675) that was not covered within that particular troubleshooting guide. In fact, I couldn’t find a solution anywhere!
It turns out that (in my case), this was caused by a mis-configured “Resource Application Policy” within “TS Gateway Manager”.
Within "TS Gateway Manager" on SBS 2008 (Server –> Policies –> Resource Authorization Policies), check that there are two “RAP” policies defined and enabled:
#1 for Connecting to "Domain Computers"
#2 for Connecting to "Domain Controllers"
If these are not present, the client will receive a “VBScript 50331675” error when trying to “Connect To A Computer” within Remote Web Workplace. In addition, an EVENT ID 301 will appear within Event Log on the SBS 2008 Server stating that the User “did not meet the resource authorization policy requirements”.