I started off with SourceSafe somewhere in the 90's, and at the time I liked the notion of "checking out a file" and seeing it locked in the database. The file was flagged by me, "mine". However, that's where the troubles started. Others want to have access to some of the locked files, and they had to ask me to check my files in. This is very bad if my changes weren't ready. Files that are not checked out are made read-only on your hard drive. People very often end up manually make the file writable so that they can edit the file without having to "announce" it to SourceSafe and the rest of the development team. When the changes were ready, people would make copy of the files, do a check out, place the backed up files back in place, and then check the files back in. The result is often that you end up erasing other people's changes.
Any professional that is familiar with other version control systems agrees that SourceSafe is just a very bad source control system. The only reason I'm even talking about it is because occasionally you see development shops that haven't ventured outside of Microsoft land. SourceSafe is simply not an acceptable solution for anyone, and I'd be glad to help put some proper systems in place.