Hi Gavin,
It sounds like you may be working on your local VSS database... It could be that the Network guys have renamed or moved your network VSS database. This will be in a VSS folder on your network somewhere.
Have a look for sourcesafe.ini on the network and that'll tell you where it is.
To check which VSS Database you're using open up VSS, click Open VSS Database in the file menu and you should have all databases listed in there. Your local VSS database will be called COMMON, any others with a UNC path are your network VSS Database. You'll be able to browse from here.
The only other problem you may encounter is if any of the files you had checked out were checked out to locations on the network that have now changed... VSS records the location you check out to and you will have problems checking these files back in, as it can't find them.
To get round this I'd locate the files that are checked out and have moved... copy them somewhere safe... undo your original checkout, check them out to a new location... copy the safe copies over the checked out files and then check in... phew.
Hope this helps,
Ben
Ben Sugden
"Remember to enjoy hunting - and that means relishing the search for the product that has never been advertised or placed handily at the front of the shop; Life begins on the uppermost shelf, avoid guide books and top 10's like the plague." - Ramsey Dukes