Until there's a new 6.2.21 xen kernel this should be a sticky somewhere...
F7 is currently a 6.2.21 kernel, but (apparently?) if you install "virtualization" it installs an older 6.2.20 kernel (the xen kernel) and this seems to break some things. On my machine, for instance, it broke my networking and also I couldn't run the nvidia-kmod (or 96xx) drivers as they are for the 6.2.21 kernel and wouldn't load since I was running 6.2.20. BUT there was no clear error message to indicate that was the cause of the problems, I just had to guess and tried removing the xen kernel, now everything is fixed. I would like to use virtualization though, I want to run a virtual Solaris x86 and maybe a virtual XP also...
I guess the xen 6.2.21 kernel will be released soon and all of this unpleasantness will go away?