Windows 7: Strange Task Scheduler/Extender problem

I've run into a problem I can't seem to permanently solve.
When my guide no longer updated, I checked the Task Scheduler and got a number of errors which all said the same thing....“The selected task “{0}” no longer exists. To see the current task click Refresh”.
Since this happened when I added an extender I searched and found the fix here: Windows 7 Task Scheduler May Not Work and Display an Error After Adding Your Xbox 360 as a Media Center Extender
The fix works but then I lose the extender. So, I reconfigure the extender and things are fine until I again realize days later that my guide is again not updating and I get the same error messages in Task Scheduler and have to apply the fix again.
Certainly something is wrong and adding (and having only 1) extender should not cause this problem. I have exhausted all other possibilities and have done nothing to this system other than adding an extender. WMC has worked flawlessly with updates.
Any ideas at all?