MS SharePoint Portal Server

I have no experience with this product and need some. The people in our real estate department use sharepoint to store their documents. When they try to disconnect a document from a category they get an error saying “you do not have access to save the file or folder properties, or there are network problems preventing authentication from the server”. They have not had these issues in the past. We are running the 2001 version. I don’t know which service pack, if any, we are running (if there isa way to find out, please let me know). It’s on a W2K server.