I've seen the neverending spinning circle many times.
Please supply full bug reports then!
The spinning circle bug for last.fm does only occur after some relocation of code when the authentification fails. (You'd need to close MP to enter the correct pass using configuration.exe nevertheless )
If you spot that with BlueTwo at any other place just report it please.
When entering no or the wrong password, the LastFM radio waiting cursor circle will wait forever and only a restart of MP can make it go away.