There is a known issue with LabVIEW running out of memory slots in it's image table
I have experienced this issue first hand and it does make LV very unstable with crashes at the most inopportune times.
Try uninstalling those toolkits and drivers that you are not currently using. In my case 8.6.1 became completely stable after that.
I had a problem that the "magic control" in this thread resolved.
This was reported to R&D (#131931) for further investigation.
What we have noticed is the larger the block diagram the more likely this error will occur. The best way to prevent this error from happening would be to reduce the size of your block diagram by implementing subVIs as much as possible.