I found the solution (for me anyway) here: http://www.talkaboutsoftware.com/group/microsoft.public.fox.programmer.exchange/messages/179275.html

All I did was select project->"clean up project" from the menu - before I upgraded. That seemed to take care of my problem. Hope it helps for you.

>Howard,
>
>No I did not try anymore, I just upgraded to VFP8.
>If you solve teh problem, let me know.
>
>Mo
>
>>Did you ever figure this out? I'm just now trying to upgrade an app from VFP8 to VFP9 and am having the same problem. The PJX/PJT is fine if I rebuild in VFP8 - but when I try VFP9, I get the invalid or missing problem.
>>
>>>Hello
>>>
>>>I am trying to compile my vfp7 application under vfp9 Beta but I am getting the error that the application PJT is missing or invalid. is this a known bug or I am doing somehting wrong.
>>>
>>>Mo