Download fix-phpBB-highlight-bug-0.1.pl or fix-phpBB-highlight-bug-0.1.zip.
IF you have ART's phpBB-2.0.10-1.src.rpm installed, I have also hacked together a .tar file to install on your Plesk-based server, so that all future installations of phpBB will include the WORKAROUND.
To install the .tar file, replace the cgitory/phpBB-2.0.10-1/apps/httpdocs-files.tar file with this one.