Stops carving/losing connection mid carve

This has happened to me several times in the last few days. I am mid way through a carve and the X-Carve just stops! The router stays running (I have it wired to turn it on and off) but it stays in the carve pattern and just stops moving. In Easel, it shows that I lost the connection (Blue carve icon) but as soon as I unplug and plug the USB, it goes green and the router shuts off.

Please help, what could be happening?

The project I am working on has several passes with different bits, and the carve times are long so each time it stops means either a wasted piece or a lengthy re-do process.

Check this thread for pointers - Carving keeps stopping (Resolved)