I've been fighting this issue for days and cant seem to find someone else with a similar issue. We rolled out 42 Dell Precision T3500 computers with Windows 7 64bit and Office 2010 64bit. Since that roll out users are experiencing slowness attaching items to emails on the DFS. A user clicks on the paper clip to attach something a windows comes up with a yellow ribbon up on top that says "some library features are unavailable due to unsupported library locations" then when they click on their dept. drive that is in the dfs a notification box with status bar comes up that says Contacting : \namespace\share\folder. This just hangs for 30-60 and it hangs every time you go deeper in a folder or you exit out. This is only affecting Win 7 workstations with office 2010. I uninstalled office 2010 and installed office 2007 and it works perfectly. I also tried office 2010 32bit but same problem. We have a mixed 2003 domain with a couple of 2008 R2 servers but primarily 2003 with exchange 2005. Any help will be greatly appreciated.