Running VirtualBox VM host on ReadyNAS Pro

I'm having trouble getting any joy with this, so I've pulled together some of the messages that I get when attempting an install of VBox and the EXT packs. I get the same failiures whether I'm on the latest 4.2.22 firmware, or downgraded to 4.2.21.

Basically, to my untrained eyes, I'm getting mixed messages as VBox is supposedly installing fine, but then I get this error... "Error! echo
Your kernel headers for kernel 2.6.37.6.RNx86_64.2.4 cannot be found at
/lib/modules/2.6.37.6.RNx86_64.2.4/build or /lib/modules/2.6.37.6.RNx86_64.2.4/source."

Anyway, hopefully the following will shed some light for somebody. With the help of a friend we've concluded that it "could" just be that my system is borked in some way, from my constant tinkering and adding bits and bobs here and there. But I'd sooner not face a total factory reset, if at all possible.

lsmod and modprobe vboxdrv outputs are below somewhere.

  OBJCOPY arch/x86/boot/setup.bin
  OBJCOPY arch/x86/boot/vmlinux.bin
  HOSTCC  arch/x86/boot/tools/build
  BUILD   arch/x86/boot/bzImage
Root device is (9, 0)
Setup is 13804 bytes (padded to 13824 bytes).
System is 3551 kB
CRC cbca6fd1
Kernel: arch/x86/boot/bzImage is ready  (#1)
  Building modules, stage 2.
  MODPOST 4 modules
  CC      drivers/scsi/scsi_wait_scan.mod.o
  LD [M]  drivers/scsi/scsi_wait_scan.ko
  CC      drivers/target/iscsi/iscsi_target_mod.mod.o
  LD [M]  drivers/target/iscsi/iscsi_target_mod.ko
  CC      drivers/target/target_core_file.mod.o
  LD [M]  drivers/target/target_core_file.ko
  CC      drivers/target/target_core_mod.mod.o
  LD [M]  drivers/target/target_core_mod.ko
ITS:/c/addons-config/VirtualBox/kernel/2.6.37/linux-2.6.37.6#

ITS:/c/addons-config/VirtualBox/kernel/2.6.37/linux-2.6.37.6# make modules
  CHK     include/linux/version.h
  CHK     include/generated/utsrelease.h
  CALL    scripts/checksyscalls.sh
  Building modules, stage 2.
  MODPOST 4 modules
ITS:/c/addons-config/VirtualBox/kernel/2.6.37/linux-2.6.37.6#

ITS:/c/addons-config/VirtualBox/backup# ./VirtualBox-4.2.2-81494-Linux_amd64.run
Verifying archive integrity... All good.
Uncompressing VirtualBox for Linux installation............
VirtualBox Version 4.2.2 r81494 (2012-10-18T14:46:00Z) installer
Installing VirtualBox to /opt/VirtualBox
Python found: python, installing bindings...
Building the VirtualBox kernel modules
Error! echo
Your kernel headers for kernel 2.6.37.6.RNx86_64.2.4 cannot be found at
/lib/modules/2.6.37.6.RNx86_64.2.4/build or /lib/modules/2.6.37.6.RNx86_64.2.4/source.

VirtualBox has been installed successfully.

You will find useful information about using VirtualBox in the user manual
  /opt/VirtualBox/UserManual.pdf
and in the user FAQ
  http://www.virtualbox.org/wiki/User_FAQ

We hope that you enjoy using VirtualBox.

ITS:/c/addons-config/VirtualBox/backup# modprobe vboxdrv
FATAL: Error inserting vboxdrv (/lib/modules/2.6.37.6.RNx86_64.2.4/misc/vboxdrv.ko): Invalid argument

ITS:/c/addons-config/VirtualBox/backup# lsmod
Module                  Size  Used by
iscsi_target_mod      244720  0
target_core_mod       264451  1 iscsi_target_mod
pvgpio                 11438  0
nv6vpd                  9334  0
ITS:/c/addons-config/VirtualBox/backup#

ITS:/c/addons-config/VirtualBox/backup# /usr/bin/VBoxManage extpack install Oracle_VM_VirtualBox_Extension_Pack-4.2.2-81494.vbox-extpack
WARNING: The vboxdrv kernel module is not loaded. Either there is no module
         available for the current kernel (2.6.37.6.RNx86_64.2.4) or it failed to
         load. Please recompile the kernel module and install it by

           sudo /etc/init.d/vboxdrv setup

         You will not be able to start VMs until this problem is fixed.
0%...10%...20%...30%...40%...50%...60%...70%...80%...90%...100%
Successfully installed "Oracle VM VirtualBox Extension Pack".
ITS:/c/addons-config/VirtualBox/backup#

ITS:/usr/src/vboxhost-4.2.2# uname -r
2.6.37.6.RNx86_64.2.4
ITS:/usr/src/vboxhost-4.2.2# cp *.ko /lib/modules/2.6.37.6.RNx86_64.2.4/

ITS:/usr/src/vboxhost-4.2.2# sudo /etc/init.d/vboxdrv setup
Stopping VirtualBox kernel modules ...done.
Uninstalling old VirtualBox DKMS kernel modules ...done.
Removing old VirtualBox pci kernel module ...done.
Removing old VirtualBox netadp kernel module ...done.
Removing old VirtualBox netflt kernel module ...done.
Removing old VirtualBox kernel module ...done.
Trying to register the VirtualBox kernel modules using DKMSError! echo
Your kernel headers for kernel 2.6.37.6.RNx86_64.2.4 cannot be found at
/lib/modules/2.6.37.6.RNx86_64.2.4/build or /lib/modules/2.6.37.6.RNx86_64.2.4/source.
 ...failed!
  (Failed, trying without DKMS)
Recompiling VirtualBox kernel modules ...done.
Starting VirtualBox kernel modules ...failed!
  (modprobe vboxdrv failed. Please use 'dmesg' to find out why)
ITS:/usr/src/vboxhost-4.2.2#

ITS:/usr/src/vboxhost-4.2.2# /etc/init.d/vboxdrv stop
Stopping VirtualBox kernel modules ...done.
ITS:/usr/src/vboxhost-4.2.2# /etc/init.d/vboxdrv restart
Stopping VirtualBox kernel modules ...done.
Starting VirtualBox kernel modules ...failed!
  (modprobe vboxdrv failed. Please use 'dmesg' to find out why)
ITS:/usr/src/vboxhost-4.2.2#

Thank you to any of you who took the time to read this post!