Hello, first post here.

When I am working on an Assembly if I make any change, such as moving an item, adding a mate, or show/hiding anything, a large chunk of the assembly will jump into a new position. This may be an entire subassembly, or even only part of that subassembly. Any parts which have jumped position become unclickable. A forced rebuild (Ctrl Q) puts it back in place.

Normally I have just used forced rebuild as its occured on minor parts in the past late in assemblies, but this time its happened on one of the very early base parts, making an unworkable mess with every click, that can't be worked around. So I really need to find a solution this time.

Has anyone had this occurance before, and know of a possible Solution? I have searched and not been able to find a relevant discussion.

The computers graphics card is an NVidia GTX 660, I'm aware it isn't an approxed FX series, but thats what the work machine has in it and I'm doubting I'll be able to get it changed any time soon - so I need to try everything else possible first to resolve the problem before suggesting a card upgrade.