Since they're not forthcoming on what to look for, not that I'd even expect them to be, have a look at the "Manually cleaning a Windows system" section in Cleaning up after an incomplete deinstallation on a Windows host and use the information to see if any of it exists on your system.
I have no problem with a product being banned from running in a Virtual Machine, that's a manufactures prerogative, however if someone is being stopped from a native boot and just because a particular software is installed... well... I personally do not use SOE however I hope some lawyer puts together a class action suit against SOE if the ban is other then from within a VM!