I first encountered the problem making a quick change to a function in an unlocked custom module in the Module Explorer before I realized the VM's disk was full. I got :
13:21:25,827 ERROR Failed to save ngppo to C:\OPENTEXT\module\ngppo_16_0_0\ospace\ngppo.oll: database is locked
and it zeroed out the .oll file.
After freeing up disk space and rebooting the VM I still get the error, and have not found anything useful searching the KB, nor searching for the error message in either the .properties files or within CSIDE.
I tried importing the code to source and saving the change there but the Java VM died and put a massive .dmp file on the disk.