Second day now, apt-get update errors here (Squeeze):

W: GPG error: http://ppa.quickbuild.pearsoncomputing.net squeeze
Release: The following signatures were invalid: BADSIG 43F1DC4F2B8638D0
QuickBuild Trinity Desktop Environment
W: Failed to fetch
http://ppa.quickbuild.pearsoncomputing.net/trinity/trinity-builddeps-v3.5.13/debian/dists/squeeze/main/binary-i386/Packages.bz2
  Hash Sum mismatch

David