Taskbar has not disappeared in over 3 days, so it appears the problem has been resolved. Previously when the task bar disappeared, there were other symptoms. Sometimes I could not get running applications to exit. Sometimes one would exit, but not the others. Sometimes none would respond. That is the reason I closed Outlook without a proper exit. I could usually get the task-manager to run by ^Alt Delete, but not always.

The problem with Outlook was not resolved by flushing the cash. It appears that the message form is corrupt in the library. I have created a custom form and it works as a workaround. But I can't make Outlook default to my custom form, so it is a lot of extra clicks to constantly change to my custom form.

Thanks for your assistance!!!