Completely uninstall messenger
Delete the messenger directory
In an explorer window go to tools>folder options >view and check the show hidden files and folders box
Go to c:\program files\msn messenger and delete winmm.dll, if it won’t delete, this is because you have messenger running - close it and try again
Reboot pc
Re-install Messenger
Put tools>folder options >view and check the show hidden files and folders box
Back to normal
Done