>>>After some testing using your code I found that following set commands
>>>move the cursor to the beginning of the text field.

SET CENTURY ON/OFF
SET DATE TO ...
SET POINT TO "."
SET SEPARATOR TO ","

>>>What all of them have in common that they could have effect on how data
>>>is pesented in the textbox.
>>Add SET HOURS TO 24 to the list.
>>Is this considered a bug or a feature? I wasted a lot of hours to find
>>out what was causing the strange behavior.
>Considering that those command are scoped to the current data session and
>the form with the affected textbox has different data session, I would say
>that it's a bug. You can report it at http://support.microsoft.com/default.aspx?scid=%2Fsupport%2Fvfoxpro%2Freport%2Freport%2Easp.

What, I actually know a KB article that Sergey doesn't? :-)

MSKB#Q313196 PRB: SET DATE Resets SelStart Property in Text Boxes

Feel free to report this as above, but make sure you make a business case for why the workaround in the article isn't good enough.