task receipts not processing

[witzend]

I sent a person a task, they completed it, the receipt showed up in my inbox
but the task did not update under tasks. I've read the troubleshooting where
they say:

"Microsoft Outlook periodically checks the Inbox for task update messages.
When a task update message appears, Outlook updates the task in your task
list and deletes the message in Inbox for you. The new task information is
saved with the task in your task list, so no information is lost."

Unfortunately my update messages stay in the inbox.
How can I force it to process my inbox?

Thanks in advance.
-mh