I have the same problem. I have upgraded my WLM to the latest version today after reinstalling the immediate previous version, which was crashing to often (Windows 7 64 bits). After I logged in the SHOW WEBCAM option was GONE for good (for bad would be more appropriate in this case). Have tried sign out/sign in thousands of times, nothing works. This is pretty lame from Microsoft. Every time I am forced to use a video call (which still works), my image quality is very bad. The Logitech Quickcam PRO 4000 webcam works perfect with all other applications. The same happens with a Notebook I have with Quickcam Pro for Notebooks, and the notebook is running XP SP3. Both machines are 100% updated, all drivers latest version. Running the ANCIENT MSN Messenger 7 shows the webcam perfectly. How come Microsoft releases a new version of WLM with a stupid bug like this? People rely on WLM for communications with friends and family worldwide. Hope someone there fix this soon, if they have any interest in doing so anyway.
If someone knows a work around (not the sign in and sign out one or disconnecting and reconnecting the webcam) it will be highly appreciated.
Good luck to us all........