Software :: Missing Autoconf.h In Vbox Install Log

I have a distro-neutral VirtualBox shell install: VirtualBox-xxx.run

you type: sh VirtualBox-xxx.run install

this goes through but the screen says "could not compile the kernel module vboxdrv.ko, see the install log"

the install log in /var/log says this:

test -e include/linux/autoconf.h -a -e include/config/auto.conf

echo " ERROR KErnel configuration is invalid
echo " include/linux/autoconf.h or include/config/auto.conf are missing
echo " run 'make oldconfig && make prepare' on kernel src to fix it"

ok, I've left out a bunch of stuff but, NO these 2 files are NOT missing. I have all the required compile-type packages and the source and headers. Under /usr/src there are :

1: /linux-2.6.31.12-0.2
2: /linux-2.6.31.12-0.2-obj
3: /linux/obj
4: linux

num 4 is a symbolic which points to 1:. num 3 has a sub-dir /i386/default which links to the /default in 2:

the supposed missing files are in sub-dir in 2:

This is what I did. I changed num 4: to point to 2:, deleted all the vbox stuff and re-tried install - still same result.

I reset num 4: to point to 1: and did the "make oldconfig && make prepare". This put new sub-dir entries under 1: with the 2 files in correct sub-dirs. Delete vbox and try re-install - still same result.

Some things I left out of the error log at the start show that the install's use of "make" relates to both dirs 1: and 2: so even with both having the files the install is still barfing.

Perhaps related to this, at the log end there are errors about the /tmp/vbox and some SUPdrv.c files.

I looked in the forums and there are suggestions wrt errors about these missing files that the fault lies with kernels 2.6.33 which puts these missing files in a different named sub-dir - /generated. Well as you see above, kernel is a 2.6.31

There's supposed to be a command line option for the shell install where you add " -- xxxxx " where xxxxx is extra instructions. I tried to put definitive pointers to the sub-dirs involved there but not successful.