Check under Preferences>Plug-Ins and make sure Load
Extension Panels is checked, then restart photoshop.
Yes Load Extension Panels was checked in plug-in preferences.
Look under Window>Extensions>Watermark
The problem is that "Extensions" under Window is GRAYED OUT and the plug-ins can NOT be accessed. I've just completed a complete reinstall of Photoshop and it's still grayed out.
It took me all day to fix this problem but right now the extensions are visible again.
Deleting Photoshop preferences didn't fix it.
Uninstalling Photoshop and then re-installing didn't work.
So I uninstalled the complete CS5 suite and hope that I got rid of everything before reinstalling the whole suite. I applied updates, installed plug-ins and it now works. What a pain. I am not very happy. I've never had to do this before and I would really like to know what turned the extension off so I don't have to go through this again. Now I am ready to personalize my short cut keys, etc.