Error during upgrade message?

[Mike]

Trying to upgrade to Dapper from Breezy via the upgrade tool and get these
error messages below. Are they fatal or just a busy server? I would like
to know what those error codes (1) & (2) mean.

Thanks in advance

Mike 

Failed to fetch
http://archive.ubuntu.com/ubuntu/dists/dapper/restricted/binary-i386/Packages.gz
Sub-process bzip2 returned an error code (2) Failed to fetch
http://archive.ubuntu.com/ubuntu/dists/dapper/multiverse/binary-i386/Packages.gz
Sub-process gzip returned an error code (1)