Some of Logitechs drivers have an option in the Control Panel > Mouse that changes the behavior of the middle mouse wheel. Chances are it was being used as a different function. You may have to play around with a few different options before you find the correct choice. I believe the default selection is "Universal scroll". You may have to change it to "middle button" or there may even be a choice for "zoom". My guess is Corel was reading the old action performed by the mouse wheel differently then it is reading the new action (duh - obviously) so you may even have to explore Logitechs website, and see if you can find the driver update lists, and see which version the old middle wheel function changed to the new function.
One caveat, this could change the way other programs behave with the middle mouse button.
Lastly, you might try under Draw's options (Tools > Options > Customization > Commands) to change some of the default behaviors for certain functions. I can't recall if v9 had these settings or not. There is now a drop down menu in the top right corner of that screen that allows you to change different behavior categories (File, Tools, View, etc), and each action can have a short cut key. The "Pan" function is under the View category. I didn't immediately see the option for assigning the middle wheel button - but it may require a quick programing shortcut to be entered to recognize text as a mouse funtion - I am not entirely sure (i.e ALT + F7, or some other Shift + Function key or something similar). Hope this helps.