Both good suggestions (the above and the higher up about finding that certain eval). It seems like if the problem ends up being in a module that's being called it would be MUCH more difficult to track down by putting checks in the local code unless I played the elimination game of removing lines until the problem goes away.
I thought I had read the debugger had a mode that would basically allow me to step through the program and see what happens as it executes. I was hoping I could use something like that to watch for exactly where/what it was complaining about.
Time to visit the friendly manual some more. ;)