I got a small POS program that use the Mscomm.ocx to open the RS232 type electronic cash drawer, the code seem like work fine in most of the PC with O/S Win98SE, WinMe, but not with WinXP, it always give me an [OLE IDispatch exception code 0 from MSComm : Port already open.] error when I try to open the port!

Is it others program or software that already use the com port already?? if yes how can I know which program or software that is using the com port?? Can I [shutdown or kill] that process?? or is it the WinXP behaviour?? Those WinXP PC is just very simple PC without running others software, just that small POS program; I even try to boot the PC under save mode, but still having the same error message problem, so can anybody here help me to solve this problem?? Thanks!!