Epson EL 486UC - Manual (Page 113)

An external device connected to the option curd is not
working correctly.
Make sure you are using the proper cable to connect the device
to the card.
Memory Module Problems
The memory count displayed by the
power-on
diagnostics
program is incorrect.
You may have installed the SIMMs incorrectly. They may be
the wrong type or speed, or they may not be inserted all the
way. See Chapter 3 for information on installing SIMMs.
Mouse Problems
Your mouse isn’t working properly or you see an auxiliary
device error message.
Make sure the mouse cable is securely connected to one of the
serial ports. Also make sure you installed the mouse driver
correctly and selected the right settings for the serial ports in
the SETUP programs. See the documentation that came with
your mouse and Chapter 1 for instructions.
6-12 Troubleshooting