Application often hangs / Drag and drop problems

I'm trialling version 6.6.0.0 with the SQL Server backend, and I've noticed that application regularly hangs, using up 100% of one of my cores.

This might be related to drag and drop problems I've had, which has forced me to disable that functionality. Often when dragging and dropping a group of sessions, they will not be dropped into the correct target, but the one just above it. Also, it sometimes looks as though it's trying to expand some groups, but nothing happens.

After it has a problem like this, and I eventually get it in the right location, if I then select multiple other groups, the CPU usage sometimes goes to 100% and the application locks up.

Not sure if others are experiencing these problems.

Thanks,

Uriah