If so, you may be having cookie problems (information left on your machine between sessions). To fix things up, close your browser,go into the 'c:\windows\cookies' directory with file explorer and delete the file named '_@.txt' There are likely to be other files of the form '_@[X].txt' where X is a number. Delete these too.
WARNING: Don't touch any other files in the windows directory if you don't know what you are doing.
Restart your browser and everything should work. Did for me.
Reg.