howardpc,
First thank you for simplifying and streamlining my code.
The flow logic for navigating the forms doesn't match the desired behavior,
however,
I've noticed the zeroing of the variable "Key" when parsing the virtual keys in the event handler, and that's the solution to the problem that has been nagging me all along. Now even my initial program works on any platform/configuration.
For good measure I've attached a revised version of your code.
Thank you very much for the time you spent on this issue.
P.S. I suspect that a similar issue could arise when using StringGrids.