Just wanted to let everyone know what I found so if anyone else has this problem it may help them.
I found in a forum post that sysinternals AutoRuns program will show you the context menus on the explorer tab.
I found that one entry for adobe acrobat 9 had a file not found when it listed the file location. So I corrected that in the registry.
I also found several entries that had file not found but the program was no longer installed so I deleted them.
Every works now. Dopus shows a context menu and Explorer doesn't crash any more.
Thanks,
JefferyS