since the upgrade to 17, I've been experiencing system freezes on frequent occasions when getting up from the computer. The term "frequent" used in this context has a different meaning from "constantly"; there are many moments when I can get up to accomplish other tasks, and come back to a usable computer without rebooting, but there seem to be as many times when coming back to a system that is using all the resources to complete some task and not giving me access for at least 5 minutes. Most of the time I end up rebooting after waiting for 5 minutes. This is a much different experience from the experience up to F16. I may be operating under the influences left by the kernel panics during the testing phase.