upgrade to ubuntu 10.04 failed

I am on Ubuntu 9 and I tried upgrade to Ubuntu 10 via update manager and also the terminal but both attempts failed.
From the terminal, I get this message "Done downloading
Done downloading

Could not download the upgrades

The upgrade is now aborted. Please check your Internet connection or
installation media and try again. All files downloaded so far are
kept.

Failed to fetch
http://my.archive.ubuntu.com/ubuntu/pool/main/c/compiz/compiz-plugins_0.8.4-0ubuntu15_i386.deb
Hash Sum mismatch

Restoring original system state

Aborting
Reading package lists: Done
Reading state information: Done
Reading state information: Done
Reading state information: Done
brian@brian-desktop:~$"

My Internet connection is active and I can browse the web. Upgrading via Update Manager also failed due to the same error as stated above.
Please help, Thank you