Hey guys, I just saw your conversation and thought I'd throw my $0.02 worth in.
By the way, Paul, if no one has said it yet, welcome to the Expert Community!
There are a few other factors that might cause this kind of behavior. The most common in my experience is a slow or unreliable internet connection. Particularly if you are getting a lot of packet loss, this can happen.
The easiest way to check for this is download PingPlotter (the free version will work fine, unless you want to try out a trial version of Standard or Pro) and install it on the Client side (your computer). Set up a trace to the Server side (your friend's computer) and watch the packet loss. If the packet loss stays below 1 - 2 % after 24 hrs or so, you should be in good shape. Otherwise, you'll need to narrow down which side the loss is on, and call the appropriate ISP.
There may also be something on the Server side that's slowing the connection process to a near-stop. The most common causes of this are a very high desktop resolution and/or a large (in file size) wallpaper photo.
This is even easier to check for: try connecting in other modes. If you can connect fine in File Transfer and Telnet modes, but not Full Control or View Only, then this is probably your issue. Ask your friend to turn off the wallpaper temporarily when you need to connect in order to fix this.
There is a slight chance that every mode will work fine except Full Control. This is more difficult to troubleshoot, but can usually be fixed by removing and reinstalling RAdmin Server.
Another thought has just occurred to me: I have seen this behavior caused by various anti-virus programs (Symantec in particular) interfering with RAdmin server. (This generally occurs with version 2.2 of the server, though I wouldn't be too surprised if some of the antivirus vendors started bonking v3.x too.)
You may want to look into putting the TeamViewer QuickSupport module on your friend's computer, at least temporarily, to give you an alternate connection method. It's a good bit slower than RAdmin, but is generally connectable under any circumstances with little setup, as long as you have internet connectivity.
Disable XP Firewall: http://www.alexnolan.net/software/disable_xp_firewall.htm
(Note: this last one wasn't mentioned above; it's a handy little program that doesn't need to be installed, and makes turning the Windows Firewall on and off so easy an end user can do t.
Especially handy for laptops.)
Hope this helps!