Dejan,

Are you experiencing a specific crash? I added an editbox to a form, and put this in the form.Click() method:

for i = 1 to 1000
   thisform.edit1.Value = thisform.edit1.Value + chr(13) + chr(10) + str(i)
endfor

I clicked the form several times, and got no crashes, although an editbox with several thousand lines of text behaves pretty sluggishly.

Perhaps you can keep only the last few thousand bytes by doing something like:

   .Value = right( .Value, 10000 ) + lcNewATCommand

>I have a editbox ( read-only ) in my app which i am using to display output commands. Is there any limitation on how many characters can be typed in this control and then my app crash. I am using the readonly Editbox to display AT commands ( talking to modem via MSCOMM32.OCX control ). If the user want to see commands they simply tick the check box but program will always print the AT commands in this editbox so am i likely to hit any boundary?
>
>Editbox is just control and is NOT linked to any source ( table field ).