Fedora: yum-complete-transaction taking forever?

It is possible that it may be in an infinite loop or such. Cleanup your yum transaction as follows:

yum install yum-utils
yum clean all
/usr/sbin/yum-complete-transaction --cleanup-only

Fedora: Remove old kernels

Update your system
$ sudo  yum -y update --skip-broken

Now remove old kernels
$ sudo package-cleanup --oldkernels -y