On 04/04/2006, at 5:04 AM, Severin Crisp in the WAMUG Mailing List digest wrote:

Help Viewer has a problem (10.4.5).  MacHelp gets to opening screen
then no links work.  All the other "helps" available to Help Viewer
seem fine.  MacHelp.help is where it should be in Library/
Documentation/Help and opens to the opening page if I double click on
it but no further.  Trashing Help preferences has not helped.
Help!

Try isolating ~/library/caches/com.apple.help.ui (or wherever it's located in 10.4.x)

Getting rid of those caches works in 10.3.9

Nancy M