Now this might be some funky windows-help cache issue, but I cleared what I thought was the cache, and it didn't help.
Executing '/help $tip', or just searching the help for '$tip', brings up an error whilst accessing the help item:
Internet Explorer Script Error
An error has occured in the script on this page
Error: Expected ';'
Do you want to continue running scripts on this page?
Yes / No
Clicking either advances to the page correctly.