It could be a file in the directory that Opus is set to show when it starts. Making it show a different directory may let you load it without the crash and then you can experiment to work out which file(s) are causing the problem and work from there to solve it.
Did you ever get to the bottom of the error 217? I see that error also, and have found that its related to Delphi - but that doesn't tell me a thing...
Try disabling all of your viewer plugins. If you can't get Opus to run to get into the Prefs dialog then you can just rename the Viewers directory to something else.
It could also be a shell extension or something else. The steps in the FAQ linked above cover ways to track that down. Most important thing is to get a lister opening with an empty directory. If you can do that then you know it's probably a file (or rather, the thing which handles the file) in the other directory which is triggering the problem.
Running Process Monitor while Opus starts can also help track things down. Often the one of the last DLLs which a process loads before a crash is the culprit. This can also help for working out why Explorer is crashing (e.g. this thread).
I think I resolved my problem. I had installed audioshell (softpointer.com/AudioShell.htm) recently. After I removed it, dopus behaves properly, no more error 217! Once I resolve some other (hardware) issues I will reinstall it and verify the connection - right now I need to keep my system running and don't want to rock the boat since my backup program is misbehaving and won't back up any more... but that's a different story
Nice one Scubaman. I have had audioshell installed for years and would never thought it could be causing a problem. After reading your post I uninstalled it and DOpus runs OK now.