Hello, I haven't encountered this problem on my home computer but on the new creative arts computer that's been set up at working I've had repeated crashes (so I think it's likely a problem with the system rather than Inkscape.)

Windows 7 64 bit, latest version of Inkscape, I occasionally get this message - "The program attempted to terminate in an unexpected manner." The window title says Microsoft Visual C++.

It's occurred while moving and duplicating objects. Anyone else encountered this?

Maybe you edited gradients with the node editor tool by selecting each step.
Try the vacuum unused defs option in the file menu time to time.