After upgrading to DF v5.0, I noticed that the Win7 start menu button on the 2nd monitor task bar stopped functioning. Through much trial and error, I've determined that there is an incopatibility with Classic Shell 3.6.5. Here's what I've observed so far:

When both of these versions are installed, I can use the start button on the 2nd screen only once, and then it just stops working completely. I have to shut down either CS or DF and restart it, in order to get it to function again. Even then, it only works once before stopping again.

To troubleshoot this, I did the following:
Reinstall DF v5.0 - menu works once, then stops (as described above)
Uninstall CS - menus work correctly.
Reinstall CS 3.6.5 - menu works once, then stops (as described above)
Uninstall CS - menus work correctly again.
Reinstall CS 3.6.1 (older version) - menus work correctly.
Reboots performed after each step above.

I'm running Win7 Home Premium 64bit.

Anybody else see this happening? Any other ideas about what may be causing this, other than incompatibility? Thanks.

I run Win7 Professional x64 with DF, Classic Shell 3.6.5, and Win Nexus docks.

I have not had any compatibility issues and every thing works without issue.

I would suggest uninstalling both, then do a good clean up with CCleaner or Glary Utilities, & reinstall.

I updated to CS 3.6.5 after installation of DF, so I'd suggest installing CS first.

That's my take. Good luck.

This seems to have done the trick. Thanks for the suggestion Mark.