I am using Vista, with WLM 8.5...... used to work great....one day the sounds stoped working and the alerts, although the sound works for video calls........Today I loaded Live Plus, still no fix to my issue, I have all boxes checked to post sounds for the actions.....the browse button to change sounds is also grayed out. When I go into windows explorer and into Live Messenger and locate the wav files, right click them they play....but they dont work in the application such as a nudge a call a sign in, etc.....
PLEASE HELP.
Thanks.........

Firstly try repairing Messenger (Add or Remove Programs>Widnows Live Messenger\Click here for support info\Repair), if not successful, uninstall it then install again.