I re-downloaded the dotLrn tarball from:
http://openacs.org/projects/dotlrn/download/download/dotlrn-2.1.3.tar.gz?revision_id=320323

I came up with the same md5sum:
f8616313b779cfad679b6a2d82b9a065 dotlrn-2.1.3.tar.gz

I get the same error with install.xml:

XML Parsing Error: not well-formed
Location: file:///local/installs/unx/dotlrn-2.1.3/dotlrn-2.1.3/install.xml
Line Number 28, Column 125:

I followed the install directions from:
http://openacs.org/doc/current/dotlrn/dotlrn-install