I have the same problem. With X1 8 installed, Outlook 2013 will start, but is completely locked up (i.e., completely unresponsive to anything, including moving or minimizing the window). The only things that seems to get Outlook working again is to uninstall X1 8. Just killing all X1 8 processes doesn't seem to do the trick.
I too am a long time user of X1. I am running Office 2013 on a Windows 7 SP1 machine.
Charlie
I too am a long time user of X1. I am running Office 2013 on a Windows 7 SP1 machine.
Charlie