virtualbox.org

i have a problem with Ubuntu 10.04.2 LTS as a guest on both Windows and Linux hosts.
i've installed Ubuntu 10.04.2 32bit from 10.04.2-dvd-i386 iso image. it runs by default with 2.6.32-22-generic version of kernel.
i've also set up a shared folder on a host system with repo mirror of i386 architecture. sf names as mirror and mounts to a /var/mirror folder already created in the guest system.
as long as i do not update guest system to a latest state, shared folder works fine - via "/etc/fstab" and via "mount -t". BUT, when i update guest system to a 2.6.32-30-generic version of kernel, shared folder cannot be mounted via any way possible. if i set up "/etc/fstab" way then at some moment of booting procedure i see a message that there is an error in fstab config and mirror cannot be mounted. if i try to mount it via "mount -t" cmd then i receive no error at all, but mountpoint is empty or i receive an error message like that "mount.vboxsf: no such device".

Host systems - Windows 7 Ultimate x64, Vista Home Premium x86, Windows 7 Home Premium x86, Ubuntu 10.04.2 x64.
Guest - always Ubuntu 10.04.2 x86.

i've no idea what this is about and how to fix it?

I understand you mean VirtualBox shared folders. This feature depends on VirtualBox Guest Additions. I think adding vboxsf support is like adding any other file system suport, it's kernel-dependent, so you should rebuild your modules. In this context, that means you should try reinstalling VirtualBox Guest Additions while running the new kernel (there may be other ways, but this is easier)

rebuilding GA modules was my first move towards solving this problem - nothing changed.

As per my Howto: Install Linux Guest Additions + Xorg config, using DKMS is recommended and should prove no future issues for kernel updates. Please use this, test it and report back.

there is one small problem - target machines have no connection to outworld and they can't have any.
and the only available source of this packages is that stupid inaccessible mirror.

these packages you rely on also depends on variety other packages. if all of them also accessible from installation ISO, then we'll be fine.

P.S. i've tested this recipe of yours on my own machine wich has the same problem - now mount give me this excuse:
/sbin/mount.vboxsf: mounting failed with the error: Protocol error

If the Host has internet, why wouldn't the Guests have that as well? All packages for kernel module compilation should be on the install ISO, it would suck if it wasn't in case you need to manually compile your network modules . Kind of like Windows that asks to look on Windows Update for a driver to your modem or LAN card, which you need to actually get on the internet .

The protocol error is noted in my other howto (see signature) with possible causes and solutions. It's sometimes hard to pinpoint what is causing it and how to fix it though.

the only host that has internet connection is my own laptop, which i cannot use - i need stable work at least on a four additional laptops, which have no internet connection at all.

P.S. looked into your second how-to.
i was using a share named "mirror", and i was mounting it to location "/var/mirror", which i've created for this specific reason.
now, i killed previous share, and created new one, with the very same path, but with name have no similarities to location pathname - it works. i will try this on other laptops tomorrow, and if it will work on them as well, then it will be another solved, but not understood mistery to me. i can understand why names of share and location couldn't match completely, but cannot understand, why they can't match partially, as in my case