This is actually a solution.
I use a great module written by KarenS called Calendar. I was frustrated when clicking on my Calendar produced nothing more than a blank page with no source code in the browser and searched in vain until posting an Issue in the Calendar module area.
KarenS was quick to respond with suggestions for my troubleshooting and during that sequence I discovered that ANOTHER module I had installed was competing with Calendar and resulting in the blank page.
My solution:
I disabled another module (disabling one module at a time and testing Calendar after each "un-check" and Save) and the Calendar module instantly began working again. In my case I contacted both developers (of Calendar and the conflicting Module) and notified them both about the conflict, as both are outstanding modules.
Simple solution to a complex problem. I hope this helps someone else as frustrated as I was!
iansears