Crash on startup : error at memory location

I had a problem with playback ofa piece with 21 MIDI channels; it was stuttering, so I tried playing with the ASIO settings. I went from the audio options window into the ASIO settings window and set the latency (buffer?) (not sure what the term was and now cannot open Reaper to check) to 500 ms. When I clicked on OK, Reaper gave me an error message on the lines of "Instruction at .... references memory location 00xx000000 which cannot be "read"" and forced a shut down. Now Reaper gives the same error every time I try to start it, so I cannot undo this setting. I specifically noticed that the memory location referenced was all zeros, which seems odd. Is there a way I can restore Reaper to the default setting short of re-installing ? Also, when I was playing back the piece, apart from the stuttering, it was frequently just re-booting the machine in the middle. Any suggestions as to what to try ? I'm using the Creative Audigy ASIO driver. I have not had problems with fewer MIDI channels, but the processor was running at about 25% until just before it crashed when the load suddenly climbed to 100%. I am running a P4, 1 GB memory, Creative Audigy ZS soundcard; for MIDI playback I was using the Synth A and Synth B, with custom soundfonts loaded. Fritz

Go Start->Programs->Reaper->'Reaper (reset configuration to factory defaults)' IIRC the stock Audigy ASIO driver is buggy. Try ASIO4ALL instead.

Thank you - simple when you know how, but I might have taken a day to find it. This forum is the best. Fritz