Ditto, except I've had two problems - both showed up around same time early 4/7  - the second one may or may not be related.
1. With gnome panel, following glibc update on SL 5.0 Boron with kernel 2.6.18-238.5.1-el5 (several reboots and logins done yesterday)
a) "I've detected a panel running" with blank (for this PC lower) gnome panel.
b) or panel shows up but is unresponsive

fix is to do  1 or 2   killall gnome-panel (if it then disappears,  execute gnome-panel). 

Problem might not show up for a login or reboot then reappears.

2. Problem #2 which I can't duplicate or get to repeat in a limited # tries
a) the PC SL5.0 lost network the morning after (4/7)  glibc update (eth0 can be stopped and started without error), but can't ping anything successfully)
from yum.log
Apr 06 06:09:27 Updated: glibc-common-2.5-58.el5_6.2.i386
Apr 06 06:09:57 Updated: glibc-2.5-58.el5_6.2.i686
Apr 06 06:09:58 Updated: nscd-2.5-58.el5_6.2.i386
Apr 06 06:10:00 Updated: glibc-headers-2.5-58.el5_6.2.i386
Apr 06 06:10:01 Updated: glibc-devel-2.5-58.el5_6.2.i386

b) switched to earlier kernel last night and things worked 2.6.18-194.26.1.el5 (could ping etc).
c) this morning went back to latest kernel 2.6.18-238.5.1-el5 and no network connectivity
d) rebooted with same kernel 2.6.18-238.5.1-el5 and this time there was network connectivity.

Wild,  anyone have a comment?
Bill Lutter