http://www.xrite.com/product_overview.aspx?ID=751&Action=support&SoftwareID=1261> (from X-Rite) Important: Version v.4.0.0 does not support the i1D2 nor the i1iSis. Customers using these devices should continue to use version v2.5.1.
I wonder if there is a "Change Log"? Is the i1D2 the spectro that comes with the i1Profiler Photo Pro-2?
I've found that my very early i1iSis serial #307 can get "stuck" and "hang" in certain semi-random workflow. "Unable to communicate with device."
i1Diagnostics 2.51 can be useful to bring it back to sanity without needing to reboot. YMMV.