GSB Campaing Keeps Crashing

I am playing the Spinward Cluster (the one with 51 planets) with the Federation, and every time I try to attack the Erriandos planet, the game crashes. In case it was a bad fleet, I backed off, lost the next planet in line, then took it back and tried again for Erriandos - still crashes. Anyone else experience this? How do I salvaed the campaign I have been playing for several days?

I am running GSB 1.56 with all of the expansions installed. I re-downloaded the latest versions of everything prior to starting play, so I doubt patching is the issue.