Sam appears to be corrects. If "No Debugging or profiling" is selected, I get the backtrace. If "Debugging" is selected, I only get the error message. And, most interestingly, if "Debugging and profiling" is selected, it runs correctly. Also, Robby's suspicion that it would run correctly if "Populate compiled/ directories (for faster loading)" is unchecked, seems to be true. It does run when it is unchecked. Doug <div class="gmail_quote"> On Sun, Jul 25, 2010 at 9:22 AM, Sam Tobin-Hochstadt <<a href="mailto:samth@ccs.neu.edu">samth@ccs.neu.edu</a>> wrote: <blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;"> <div class="im">On Sun, Jul 25, 2010 at 8:27 AM, Matthew Flatt <<a href="mailto:mflatt@cs.utah.edu">mflatt@cs.utah.edu</a>> wrote: > > It's worrying, though, that you're getting a DrRacket backtrace that > covers "cm.rkt". Files in the main installation normally should not be > instrumented for backtraces. Does your installation have any "drracket" > subdirectories of any "compiled" directories? </div>It's easy to get such a backtrace if "Debugging" (meaning Errortrace Debugging) is off. This is particularly likely to be what happened here, since every backtrace frame is a function definition, which rarely happens with errortrace, but always happens with the internal Racket backtraces. -- sam th <a href="mailto:samth@ccs.neu.edu">samth@ccs.neu.edu</a> </blockquote></div>