Our forums are always undergoing trimming of old posts / attachements, etc.. if you are trying to access a post and get the error:
An Error Has Occurred!
The topic or board you are looking for appears to be either missing or off limits to you.
then try searching google for the thread using google site search and the topic id from the url:
ie.. if the missing topic has the url:http://www.pclinuxos.com/forum/index.php?topic=53673
then use the following search in google:
..if you are lucky there will be a link to a cached version of the topic at the end of google's description of the page.
For old wiki pages, etc, you can also try the wayback machine at http://web.archive.org/