Problems with Pocket Outlook

I purchased a refurbished Aero 8000 HPC Pro about a month ago, and in the last couple days it's developed problems with Pocket Outlook. The problems started after I synched the Aero with my desktop PC through its docking port. While it was docked, I made several changes to appointments and tasks in Outlook on my desktop PC; these were transferred to the Aero without a hitch. But later, I was unable to assign a category to items in the Tasks folder on the Aero. First it wouldn't let me select a category, and then the category list refused to open at all. Then, Tasks stopped opening altogether. I can still see existing tasks when I have the calendar in Agenda view, and I can open them by double-clicking, but I can't assign categories, can't create new tasks, and still can't open Tasks directly.

Then today, Contacts wouldn't let me view individual contacts. I can open Contacts and see the full list, but when I double-click on an individual contact I get an empty window.

Anyone have ideas on what is happening, and what I can do to fix it? Thanks.