Working in an evironment where multiple SVN users should be able to edit files in a checked-out folder, update, and commit changes. It took FUCKING FOREVER to figure out what we were doing wrong. No matter what, whenever anybody tried to do an SVN update, commit, or even diff, it would ask the the password of a particular user rather than prompt for both user id and password.
Web site after web site advised how to clear the saved authentication data from the "Settings" dialog, which I did. I even did the nuclear clear-out option of clearing subdirectories from the "auth" folder in Documents and Settings.
What is not explained is that no matter what you do, if a folder has been checked out by a particular SVN user with "Authentication Saved", there is no way to make it forget what user checked it out.
The solution was to move the folder checked out by the previous user, then check it out again after having cleared the saved authentiation. This time, during the checkout, it asked for the user id, and I didn't check "save authentication". Now everybody can use Tortoise on the files in this folder, and it will ask for their user name for every operation.