A reboot is a reboot and has nothing to do with the problem.
As mentioned earlier, many many people are running windows 8.1 with 360 and it's working fine for them.
Please download the most recent version of 360.
Then uninstall your version from the control panel using the option to save all settings.
Reboot the system and verify all your Metro apps actually work.
If they do, re-install 360, reboot and verify they still work and then you can run liveupdate until it's fully updated.
If your Metro apps do not work after uninstalling 360 you need to first resolve that issue.
Best of Luck,
Dave