You have Visual SourceSafe 2005. When you try to log in with a valid user name and password, the login dialog flashes and does not allow you to open the database.
The User.txt file is not located in the folder with the SRCSafe.ini file.
Locate a valid User.txt file and place it in the same folder as the SRCSafe.ini file.
If you cannot find a user.txt file within the structure of the database, you can go back to a backup of your VSS database and use that User.txt file.