I was unable to scroll horizontally using the trackpad in Excel 2010 on Windows 7 Professional guest OS.
Build 9.0.24229 (Revision 991745; Tuesday, April 1, 2014)
Horizontal scrolling worked in IE 11, but not in Windows Explorer or MS Office apps.
After taking the following steps with Support it was fixed:
1) Mac System Settings: enable 2 or 3 finger swipe in Mac trackpad
2) PD VM Configuration: Set: Do not Optimize for games in VM configuration for both keyboard and mouse.
3) PD VM Configuration:Enable smooth scrolling.
Combine all 3 specific settings and, voila!, it works. I have no idea why. (along the way we removed and reinstalled Parallels Tools a couple of times, repeatedly quit all open apps in the VM, and restarted the VM multiple times.)
The fix is only temporary though. You will periodically need to switch from 2 or 3 finger swipe to 3 finger swipe, then quit and relaunch Excel. Then the horizontal scrolling works again.
It's definitely an annoy software quality issue. The feature should just work without constant tinkering.
I hope this helps the next person who comes along.
Adam
Last edited: May 21, 2014