Checking for a defective Serial Port.
In Windows 95 you can determine whether a serial port is active and operational through the use of a serial mouse. Windows 95 will automatically try to locate a mouse whenever it is started, regardless of the current configuration.
Your first step is to acquire a serial mouse. If you do not already own one, try borrowing one from a friend, neighbor, or colleague. Remove any other mouse you have attached to the system. Shut down the computer. Connect the serial mouse to the serial port the docking station was attached to. Restart the computer. If you receive the message "Windows did not detect a mouse", then there is a problem with the port. It may need to be replaced. Contact your computer manufacturer for more details.
Another possible indication of a defective serial port comes through the Windows 95 Control Panel. Select Start/Settings/Control Panel/Modems/Diagnostics. Highlight the COM port number in question. Select More Info. A greyed-out entry for UART could indicate a problem with the serial port. However, it could also mean that another application or device is controlling the COM port.