Download OK but files wont work

[Rehab]

I've been using version 0.59.6.8 sucesfully for some time now. I can still download files OK but nothing that I've done recently will work. Windows media player gives me error messages for MP3's - 'The file you are attempting to playhas an extension that does not match the file format. Playing the file may result in unexpected behaviour - Do you want the Player to try and play the file'. I get similar messages from other programs for other file types.

Dont know if I'm being paranoid bt this started at the same time that I started getting messages asking me to upgrade to version 7.

Anyone got any ideas for the new boy??