What do you mean “if you go in too deep”? I have a Zoom R24 that I use with Windows 7 and Windows 8; I currently have it ordinarily set up as my soundcard on my Windows 7 machine. It doesn’t cause my machine to crash. My experience with the Zoom R24 and H4n is that if I try to reduce the driver latency too far, the driver stops working - but it doesn’t crash Cubase. This has been my experience with Cubase 6.5 32 bit and 64 bit, and now Cubase 7 64 bit.
Are there reproduceable steps that cause your machine to crash?
Steve.