At Chaosgroup we take any bugs related to crashing / freezing very seriously. We have recently released an update that resolves all the issues we have found related to that. We do not know what your 3dm / model / computer has for specs and how it might affect freezes, so we cannot say we have resolved all issues, but we are pretty happy with the latest builds. You should of received an email from Chaosgroup about a new SR3 build as mentioned here: New V-Ray Service Release (#3)
In this latest build if you are able to duplicate freezes / crashes / hangs feel free to send the file, with version number, and computer specs to: vrayrhino@chaosgroup.com or support@chaosgroup.com, and we will look into it further.
Matthew Newberg
V - Ray For Rhino Developer