rewire crashes

I've written a program in Max that loops MIDI data and sends it over rewire to Cubase 6 which is hosting my VSTs. Every few minutes or so, Cubase will all of a sudden stop receiving MIDI data from Max. When I reinitialize the ad_rewire driver, I get my connection back and Cubase starts receiving MIDI data again. There doesn't seem to be any pattern to when it happens. Sometimes it's while I'm recording data in, sometimes it's while fiddling around with my VSTs in Cubase, and sometimes it's while I'm doing nothing. I interpret this as the ad_rewire driver crashing, though maybe someone else has a better idea. My first guess is that it might be because I'm running Max on a 64-bit Windows 7 machine. However if anyone has any ideas as to what else might be causing the problem, I would like to try those first. Going through the hassle of adding a 32-bit Windows 7 partition onto my hard drive doesn't sound like fun.