OK, looking into what triggers that error message number, it must be coming from the MDL options form. It suggests that you must have a test in your ADE XL setup which has the MDL Control options set, and is referring to a library which is no longer in your cds.lib.
So, I'd suggest double clicking on each test, bringing up the ADE XL test editor, and then going to Simulation->MDL Control...
The libNameSel is the name of the Library field (used if MDL Control File is set to "From cellView"). Maybe you need to fiddle with this to point to a valid library and then OK the form (even if "Enable MDL Mode" is turned off), and then close the ADE XL test editor to save it.
Worth a try. I'm pretty confident that the message is related to this form, since libNameSel only occurs on this form.