Altium 09 Copy Footprint between libraries
If I recall correctly, Altium will go into kind of a read-only mode if you don't have the appropriate license checked out. There are two levels of license and only the higher one permits modification of PCB layouts. Check that your network license server is working correctly (assuming floating licenses) and that you have the correct type of license checked out. 

This can be a real face-palm moment if you own both full and schematic-only licenses.