Hi fr4nk,
yep, this is the odd bug we had-hadnot-haveback for quite some time.
As a workaround, launch
http://www.os2world.com/forumThis will launch the forum "unframed" (which resolves the problem)
Next, enter an accurate string for the thread title into the "search" entry field in the right upper part.
In your case, this would be "pretty-print".
Perform the search - and one of the first results should be the link to the thread.
Click it and it will load the thread.
Sorry if there is perhaps a more elegant or efficient way of doing this, but this works for me.
I know it's nasty and cumbersome... but this will perhaps change only once os2world.com shifts to a different (or newer) forum software.
The cause seems to be something in the SMF-Joomla bridge component. I have no idea what exactly the problem is though...
Hope this helps
Thomas