I think I've figured it out...whenever you type PlantFiles, it's programmed to automatically turn that into a link to Plant Files. So when it sees PlantFiles inside our links, it turns that word into a link to Plant Files and in the process messes up the link that you were trying to make to the forum.
Well, I suppose linking to PF is more important than linking to this forum, if that's the choice. Maybe Dave could intentionally mis-spell PF in the url so this didn't happen - but then there'd be posts about that. haha.
Okay, thanks ecrane
Or he could just do an underscore or a dash or something in between the words...make it say Plant_Files in the forum link, then it's still spelled right but the link will work right. My guess is not too many people try to paste links directly to this forum though so I'm not sure if it's worth fixing or not!