Using SQLyog Enterprise v5.2 Debug:
I opened the program, and opened 2 connections to 2 different servers. The servers have a LOT of databases with a LOT of tables, so the status message at the bottom of the Yog was going crazy with the “building tag files” or whatever it says. I opened the 'Preferences' dialog and turned off auto-complete. After doing so, the status bar still said it was building the tag files, so I closed each of the two query windows I had open. As soon as I closed the 2nd one, the Yog crashed. Error log attached.