Hi,
I suspended R# 6 and restarted VS2010 this morning. So far VS hasn't crashed, which is great. There is still a gradual rise in the private bytes associated with the VS process, but it is nowhere near as fast as when R# is activated.
I'd say that R#6 has been responsible for the recent crashing behaviour I've experienced, although the gradual rise in private byres is still indicative of a memory leak of some sort, so there may well be another issue to be resolved. Whether that's in nCrunch remains to be seen :-)
rikrak