Sounds like a corrupt installation. 
Uninstall it.. then do this.
If using a Windows Machine:
restart, and install the player in Safe Mode (to start in safe mode, start tapping F8 right after you press the power button). 
for a mac. just hold down the shift key during startup. 
After installation, just restart, and you will boot back into normal mode with everything installed. 
Hope this helps, 
-Lou