My daughter has a weblog on Xanga that recently stopped showing her updates when she used Safari or Firefox (on my iBook and on Windows). When she visits her site she is unable to see any recent changes, which makes it look like a caching issue.
Internet Explorer works fine with Xanga (it is a .net site...) on the Mac and Windows, but we do not like using IE for many reasons. Xanga's help site suggests that the problem is a local cache issue, but after disabling the local cache using some hints from this site, it still behaved the same way. I also tried the site in OmniWeb (which did not have a cache of the site), and it had the same problem.
To fix it, I enabled the Debug menu in Safari, set the user-agent to "Windows MSIE 6.0," and it worked! I have sent Xanga an email explaining that it is not a local cache problem, and asking them to fix their site. Oddly, I have not heard back.
This is an old solution (there have been numerous hints that address this type of issue), but I was unable to find any mention of Xanga and Safari/Firefox problems, so maybe some others will find it useful.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20041214203839976