解决：/etc/init.d/vboxdrv setup

So here is how I installed VirtualBox on a PAE kernel

uname-a
Linux xxxxxx 2.6.18-128.el5PAE #1 SMP Wed Jan 21 11:19:46 EST 2009 i686 i686 i386 GNU/Linux

On initial install of Virtual Box I had the following error:

VirtualBox-2.2.4_47978_rhel5-1.i386

Creating group 'vboxusers'. VM users must be member of that group!

No precompiled module for this kernel found -- trying to build one. Messages
emitted during module compilation will be logged to /var/log/vbox-install.log.

Compilation of the kernel module FAILED! VirtualBox will not start until this
problem is fixed. Please consult /var/log/vbox-install.log to find out why the
kernel module does not compile. Most probably the kernel sources are not found.
Install them and execute

/etc/init.d/vboxdrv setup

as root.

After hours messing with Xen kernel I was expecting as much!
So as recommended I carried out the setup

/etc/init.d/vboxdrv setup
Stopping VirtualBox kernel module [ OK ]
Recompiling VirtualBox kernel module [FAILED]
(Look at /var/log/vbox-install.log to find out what went wrong)


Darn, here we go again..
So I updated headers for PAE kernel.

yum install kernel-PAE-devel
export KERN_DIR=/usr/src/kernels/2.6.18-128.1.10.el5-PAE-i686/

Tried the setup again but forgot that I had a clean install of centos so had to install gcc!

yum install gcc

and redid the setup

I still had errors as the compilers could not find the headers.

** Compiling vboxdrv
Makefile:145: *** Error: unable to find the sources of your current Linux kernel. Specify KERN_DIR= and run Make again. Stop.

The following declaration stating where the correct headers were did the trick.
(Note that this directory depends on the kernel version!)

export KERN_DIR=/usr/src/kernels/2.6.18-128.1.10.el5-PAE-i686/
/etc/init.d/vboxdrv setup
Stopping VirtualBox kernel module [ OK ]
Recompiling VirtualBox kernel module [ OK ]
Starting VirtualBox kernel module [ OK ]