It's hard to say what the issue might be if it is just crashing randomly while running your code. Is the crash 100% reproducible (i.e. happens every time), or is it more random? Does you code involve rending many graphical items?
You might find IDLDE to be more stable if you launch it with the outofprocess flag to separate the IDL and Java processes. To do this, run it through the Windows Command Prompt like this: C:\Program Files\Harris\IDL87\bin\bin.x86_64\idlde.exe -outofprocess