Had a look at your code:
Not sure what the purpose of this is. Why are your storing the pointer to the ComboBox in the ComboBox's own string list?
You can access the pointers in the string list by calling:
However, the pointer value returned will always be the same the Sender pointer in an event, such as the ComboBox's OnClick event:
Why don't you just initialise the boxes with string values, and respond in an click event based on the newly selected index value or text string.
void __fastcall TfrmComminit::combocomportClick(TObject *Sender)
You could store this somewhere as either an integer index value, which maps to a baud rate, or a string which maps to a baud rate?