Hi there,
Like many of you, I got the dreaded drag-and-drop issue after installing the displaylink drivers on my MBP 2008 (version 2.0). Totally messed up my workflow
so I uninstalled it (thanks for the uninstaller guys!!) and everything worked fine again. However, this meant no extra display.
The funny thing is however that I did not get the same problems on my MB 2008 Unibody so I got the idea that maybe, just maybe, something went wrong during the installation on the MBP. To test this, I re-installed the 2.0 drivers on the MBP and, to my welcome suprise, all seems to work fine. I rebooted and done several shutdown-boot-ups to see whether the problem re-appears. So far, no problems.
I don't know of this all makes any sense and to be honest, I don't really care as long as works again.
Hope this helps also with others!
Good luck!