Re: fedora16 system goes to Emergency Mode after a yum kernel update and reboot
First, post exactly which kernel is giving you problems since other people may have solved them. Tell what hardware you have.
Use the command line to look in the log files in /var/log for errors. (Look for actual errors as opposed to warnings or debug printout.) It will be useful to reproduce the error and note the time (synchronized with the computer clock) when it happens to the nearest second since the important log /var/log/messages has time stamps.
See if any core dumps are recorded (as directories) in /var/spool/abrt.
At some point, you should boot with an older kernel to determine if a new kernel is a fault rather than some hardware problem that has cropped up.
"Never let the task you are trying to accomplish distract you from the study of computers."