Problem installing RevWeb plugin

[Petrides, M.D. Marian]

I'm having the devil of a time getting the RevWeb plugin to install on  
Windows machines running Internet Explorer.  I have a couple of stacks  
installed on my OnRev server that I can access and run just fine from  
multiple Macs and also from a tablet PC on which I had previously  
installed the plugin.

However, when I try to access the URL from several different PCs on  
three different networks, both at home and at work, I keep getting the  
message that the plugin needs to be installed.  I install it and try  
the site again and get the same message--this despite the fact that  
Manage Add Ons in IE shows the plug in to be installed and enabled.

I've tried this on 4 or 5 different Windows machines, running  
everything from XP to Vista, and using both of my stacks. I've tried  
restarting IE, rebooting the computer, everything I can think of.

Does anybody have an idea what the problem is?

TIA.
--Marian