I have the same problem as this, Linux Mint 17.3, 64 bit, AXEpad crashes when trying to save a file, or sometimes when trying something else, like a cut and paste. I've tried all the fixes suggested here, to no avail. Right now the only way I can code with this machine is to write code in Gedit, save it with a .bas filename, open it in AXEpad, check the syntax etc, programme a Picaxe, then close AXEpad, open the file in Gedit to edit it etc, etc.
I'm far from being a Linux guru, but have been running Mint for a couple of years on two machines, one of which is my everyday browsing the web laptop. I only use Windows on an older PC in my study, which happens to be the one I used to use to write Picaxe code on before I moved my "workshop" bench to a nice new workshop!.
I've switched to using this 64 bit Linux machine in the workshop as it has real hardware serial and parallel ports (the latter very useful for driving my little bench top router) and programming Picaxe chips via a real serial port in Linux seems to be a fair bit quicker than using the AXE027 plugged in to the Windows machine in my study.
If anyone has a foolproof way to stop AXEpad crashing, then I'd be very grateful indeed, as it does get a bit frustrating if it crashes just after I've edited some code in it and before I've managed a successful cut and paste to Gedit.
FWIW, if I open AXEpad from a command window then when it crashes it reports the same as mentioned above "Segmentation fault"