After I make some operations to update Kernel, my fedora 12 are stopped on the previous page of login, and also can not show the mouse point after the color of fedora logo changed from white to colorific in rebooting(it also spend several minues on this page, and then halt even I take a two hours' snooze and it still didn't change anything

).
That's the details:
Before the update:
uname -r: 2.6.31.20-174.2.22.fc12.i686
Then, I execute:
yum -y update kernel kernel_headers kernel-devel
(kernel and kernel_headers are updated successfully, and I canceled the update for kernel-devel as the slow downloading speed, and kernel-devel are updated few days ago)
After the update;
uname -r: 2.6.32.10-****
And, I found I have two kernels in my system:
rpm -q kernel:
2.6.31.20-***
2.6.32.10-***
and for kernel-headers/kernel-devel:
rpm -q kernel-headers kernel-devel:
2.6.32.10-****
2.6.32.9-****(updated few days ago)
Then, I try to un-install the older kernel by:
rpm -e kernel-2.6.31.20-***
after that:
uname -r: 2.6.32.10_***
rpm -q kernel: 2.6.32.10-***(One kernel left)
Then I reboot, and halt before the login page. Could anyone help to tell what's wrong, and how to fix this problem? Thanks so much!
BTW, I use KDE