dea friends when i am connection serial mouse to any of the com port the proffessional version of win2k is hanging it is workig perfectly well in ps2 port .i removed my network card and modem .but it is showing the same problem.i want to connect one serial port device in that one.what can i do i checked this system with another harddisk containing win98 it is working well i chamged the motherbord also .is there any problem in win2k proffesional with serial port.

You have a conflict here; echos of serial mouse and APC functions come to mind, similar to NT4... http://support.microsoft.com/default.aspx?scid=kb;en-us;149446 may help explain further? Also serial rodents (mice) don't appear to work in Safe-mode...; see: http://support.microsoft.com/default.aspx?scid=kb;en-us;236850