|Here are some things to try not necessarily in the following order. You decide that.|
If there is a printer connected as well, disconnect it.
Look at the event viewer for errors.
Open the task manager. End processes that you think might be causing the error.
Go into the BIOS and change the com port, if that option is available.
Look for IRQ conflicts.
Try it in safe mode.
Look for command line options to start the program instead of clicking on it.