Upgrade kernel 20-16=error message

amy

I  received 3 updates, I installed 2 of 3 but the 3rd, linux-image-2.6.20-16 generic, dosen't work. I received this error message:

E: /var/cache/apt/archives/linux-image-2.6.20-16-generic_2.6.20-16.29_i386.deb: unable to make backup link of `./boot/config-2.6.20-16-generic' before installing new version

I have a toshiba portege 3500 tablet PC and I install  via Wubi.
Thanks.