Just did an upgrade install of the current Win10 preview.  Already had Start8 installed, and it worked (at least somewhat) after the upgrade.  Went to install the trial of start10, and did a reboot.  It got trapped in a loop with both start10 and start8 trying to load.  This caused a lot of flicker and was unusable.

Was able to Ctrl-Alt-Del to get to taskmanager, and found BOTH trying to run.  Killed the start8 service, and then was able to uninstall it.  Things seem to be fine now, but installer SHOULD be able to detect if start8 is running to stop AND uninstall it.

Keep up good work!  Best menu, and well worth the money!