I know this is an old post but as one who also faced the same issue, the solution is simple. Upgrade to 14.04.4. The issue is caused by some kernel incompatibility with hardware on XPS 8700, kernel 3.18 and 3.19 seem to fix it.
-- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1389006 Title: [Dell XPS 8700] USB mouse and keyboard unresponsive after last update To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1389006/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
