Another way to slow down your clips:
1) Press Ctrl+A to select all events
2) Press G to group them
3) Hold down the Ctrl key and drag the right edge of the rightmost event to slow down (drag to the right) or speed up (drag to the left)
Open the Explorer and type %APPDATA%\Sony\Vegas Pro\Application Extensions in the address line. Hit Enter. Delete the PA library (with .dll extension). Reinstall if you need.