Try installing ForceAspi (you can get info here: http://www.flexion.org/aspi/, you can download here: http://www.psxemu.com/epsxe/tools/ForceASPI_1.7.zip (you might have to right click and choose save target as...)). I assume you get this error when you click either the Config menu option, or try to configure plugins? I had this too, and installing ForceAspi should take care of it. 