i am using ikonboard, a free flatfile forum written in perl which is nicely supported with its own help forum.
available here - http://www.ikonboard.com/
The only problem i came across was when i tried to remove the files from my webspace some of the permissions that the program had set itself meant some folders could not be deleted but i have been advised by freeola to use fileman (available here - http://www.gossamer-threads.com/scripts/fileman/) which installs on your webspace and is used to upload and control files,(i had to move the images folder into the cgi folder for it to work) so far i have not needed to delete anything but i should be fine.
ikonboard is easy to set up and can be modified in many different ways, from basic colour and icons, to easily editing the main html code.
if you want to have a look at it i have just started setting up my website which you can visit at www.zootworld.com, the forum is held in a frame inside a html page.
make sure your you upload the files correctly using ascii and binary uploads and that the permissions are set correctly though i think this applies to any forum.
if you have problems with it just post here and i will try and help or go to the ikonboard site















