I've had one of these for years. Pretty straightforward. Your cable(new) will probably meet IEEE 1284 (bi-directional comms) requirments. Do what CJ says and check the BIOS. Have you installed the ESM? ie Epson Status Monitor. Quite a good diagnostic tool.
I couldn't get mine to work satisfactorily on a WinME PC through a LAN. But never had any trouble on Win 98SE (You should bin Win 98 Orig Ver) or Win 2000.
If it works, don't worry. Just use it in spite of the error messages.