David-

>I am getting some weird performance with the treeview control in VFP 6.0. After clicking several times on different items in the treeview the selected item no longer remains highlighted. The highlight will go to one particular item and the dotted rectangle will surround the
>item I click. I continue to click other items and the hightlight works on mouse click down but as soon as the mouse up occurs the highlight goes back to the same item leaving only the dotted rectangle surrounding the item I click.

I don't know, but since you haven't gotten any suggestions yet, I looked it up in the MSDN KB, and found this KB article that *might* help: Q190309
http://support.microsoft.com/support/kb/articles/Q190/3/09.ASP

If that doesn't help, then it would be helpful for us if you:
1. Tell us your OS
2. Are you running VS service pack 3
3. Have you looked in the KB already?
4. Can you make a runnable example of this behavior. If it is an unreported bug, then we will need to have this for reporting it to MS.

If you do resolve it, please post back here with what the solution was. Thanks. :)