I have no hard evidence of cache corruption. My opinion on it is based on the number of Forum posters with serious site problems for whom clearing the site cache in the Manager didn't work, but deleting the files in the core/cache folder did.
It seems to me that I saw a lot more of these in the early 2.0.x releases, though it still seems to occur. It's possible that all of them come from people with substandard hosting, but IMO, it would be better if MODX didn't crash on those platforms. I don't think WordPress does, but I could be wrong.
------------------------------------------------------------------------------------------
PLEASE, PLEASE specify the version of MODX you are using.
MODX info for everyone:
http://bobsguides.com/modx.html