Open a random .py file with classes (just about all of them do) in SPE and try to change the name of any class. SPE will promptly segfault. There's no backtrace, suggesting that either the Python interpreter or one of the C libraries pulled in segfaulted.
Hold on, I had discovered that I was running SPE as root. Running it as my normal user (who owns the file) appears to work. More to come.
OK, it only appears to happen when SPE is run as root, and when root technically doesn't have write permissions to the file being edited (e.g. the file is perm'd 1000:100 0644). The obvious workaround is to either drop down to normal user, or make a copy of the file that root CAN write to.
This needs to be fixed upstream - thanks for your bug report.