cannot update XFree86 packages

[MDS]

Hello.
I know that there are up2date issues, and one of mine is not having any 
of the XFree86 packages listed as available to update. They were there a 
couple of days ago on the Available Updates Window, but now they're 
gone. I have not updated these packages. I have similar issues with some 
glibc packages, among many others, all of which I have not updated.
Much thanks.
Mark