I've finally narrowed down what was causing Objectdock to freeze.
Switching the task-bar to autohide (or asking ObjectDock to hide it for me) causes OD to freeze. Occasionally I can interact with it, get icons to move a few pixels, etc. This also causes the task manager to begin responding very slowly.
If I switch the task-bar back to non-auto-hiding, after a few minutes everything sometimes comes right. It's easier to kill OD and reload it.
This is present in both the alpha from Impulse and the beta from the old stardock app, whatever it was. I'm fairly certain I was able to reproduce this in the release version as well. It didn't always do this, but it does do it regardless of any plugins that are loaded. It could be a conflict with another utility but I haven't had time to find out if that's the case.
Running: Vista Home Premium 64.
Like many other people I'd like to see OD updated for Vista 64 and the bugs ironed out so I can load the system tray bar and do away with the task bar entirely again. Please don't make us wait too much longer.