>Unfortunately we have not yet been able to reproduce this or find a possible cause.

To help reproduce this, I have:
-Windows 7 (x64)
-Machine in a domain
-Outlook 2010 (v14.0.6129.5000 (32-bit))
-PL/SQL Developer 9.0.6.1655

Also, I noticed that Special Copy (C#, C++, etc) always works fast. You must be doing something differently on those commands, and that might help track the problem.