Unfortunately, I have not found a 100% pattern for when this occurs.
here are the symptoms;
SQLDeveloper will permanently hang with a busy cursor (spinning disk) and never return.
It seems to happen when trying to access the database. For example, I was editing a procedure, and I double clicked on a table to bring it up in another tab, and it just hung. I have also had it happen when trying to compile procedures/packages.
The only way out is to stop the process, losing my work.
My Environment;
Windows 7 fully patched on an I7 9 GB memory. The databases that I access are on another network connected via IPSec VPN.
I suspect a network problem, but i do not see any VPN drops during the time the problem happens. I ran a constant ping from my workstation to the server with the DB and do not see dropped packets.
This is quite frustrating.
Paul