Intermittent Issue Opening a Solution with SourceSafe Internet Plug-in

Question

Hello, I have a weird issue with VSS that is happening with both Visual Studio 2005 and 2008. I have a quite large solution containing about 80 projects. I work remotely from the main office and use the internet plug in to manage source control, the source is hosted in the main office and I am connected via ADSL broadband. Sometimes when I open the solution, I am asked for the VSS login name & password and the solution loads fine. At other times however it prompts for the username & password, starts to load the solution and loads 5-6 projects, then hangs. I've increased the timeout to 2 hours with no effect. Weird thing is it always stops at the same point, at the same project. So, sometimes it loads fine, other times I get this hang at a specific point. I can tell when it's going to hang, as the load seems slow. I think I can rule out firewall/anti virus type issues (because it works sometimes) and I think the office setup must be OK because other remote users are not affected. I suspect there must be something in my environment/internet connection that is the cause. I have 2 PC's that both seem to be affected in the same way. Question is, what could be the cause ? All other stuff that relies on my internet connection such as email, remote desktop connections, internet browsing, etc are all unaffected - what could be affecting SourceSafe when everything else is OK ? Is there something unusual about how SourceSafe communicates that could be getting upset ? Can you suggest anything I can try/check ?