[CentOS] yum and wildcard problems

I am having trouble using wildcards ("*") with yum in Centos 5.  Listing
or installing packages using them just immeidately fails with a "No match"
error, and I'm not sure why.  Here is an example.  Any comments?  I'd love
to fix this.

[root at granta ~]# ps -e | grep yum
 2706 ?        00:00:22 yum-updatesd
[root at granta ~]# yum list | grep kern
kernel.x86_64                            2.6.18-8.1.1.el5       installed
kernel-devel.x86_64                      2.6.18-8.1.1.el5       installed
kernel-headers.x86_64                    2.6.18-8.1.1.el5       installed
kernel-doc.noarch                        2.6.18-8.1.1.el5       updates
kernel-xen.x86_64                        2.6.18-8.1.1.el5       updates
kernel-xen-devel.x86_64                  2.6.18-8.1.1.el5       updates
yum-kernel-module.noarch                 1.0.3-1.el5.centos     extras
[root at granta ~]# yum list kern*
yum: No match.
[root at granta ~]# yum list kernel
Loading "installonlyn" plugin
Setting up repositories
Reading repository metadata in from local files
Installed Packages
kernel.x86_64                            2.6.18-8.1.1.el5       installed
[root at granta ~]#

Similarly, something like "yum install xorg-x11-font*" would fail with a
"No match" error, but the packages show up in a full list.

The machine is a fresh x86_64 install from DVD, yesterday.  I previously
ran CentOS 4.4 on it with no problems.

-Brian