I didn't file an issue since is seems to be a dup of:http://youtrack.jetbrains.com/issue/WI-20882
This started happening when PyCharm said it was running out of memory and popped up a dialog box suggesting I increase the memory allowance. Since the memory allowances were 512/259/64 MB I just doubled them all since I have 16GB.
After rebooting with only 5GB used and 10GB of memory spare I still get the error code 4.
Reducing the Xmx memory back to 512 MB in the pycharm.exe.vmoptions file solved my problem, at the risk I guess of potentially running out of memory again with my large projects.
I assume this is a limitation because PyCharm is 32bit? If so, is there a 64bit version available or planned?