Did you try on enother PC? Maybe there's a problem with a com port on that PC.

>MSCOMM32 on Win2000 Professonal PC with VFP6 SP5 install and
>Win2k SP3 install
>
>>What kind of control are you using to communicate with COM port?
>>
>>>
>>>My application occasionally had this C0000005 error and the screen
>>>will show the calling program line and below is the line that
>>>indicate causing the problem. The STX,ETX and DLE are constant
>>>define in the header file. It will output some character to the
>>>COM port. Anyone had any ideal how to solve this problem.
>>>
>>>Thank you very much
>>>
>>> lBuf = INT(VAL(lChar))
>>> IF lBuf = STX OR lBuf = ETX OR lBuf = DLE
>>> THIS.OutPort(CHR(DLE))
>>> lLRC = BITXOR(DLE,lLRC)
>>>
>>> ENDIF