If you are experiencing Firefox download problem, in which case the Download window no longer shows up when performing download and "Save Page As" is no longer saving any web pages, your Firefox configuration file might have been corrupted.
I had this problem for almost three months now. I have tried almost anything that I can think of: clean install, messing around settings in Options, removing themes and extensions. None of which have worked. Problem persists until recently I ran into a site which is trying to solve exactly the same problem. It turns out my Firefox download configuration file, downloads.rdf, is corrupted.
Update (8/14/2007): This article is outdated due to incompatible of Wikifilter and the latest Wikipedia XML dump file. Check comments for the workaround.
Although the credibility of Wikipedia is not well respected among academic communities, that doesn't stop Wikipedia from becoming the most popular encyclopedia on the web. According to the update-to-date statistics, the English Wikipedia contains almost 2 millions articles. Don't scream if I tell you that you can store all articles in English Wikipedia in your computer and view them locally, because you can.
The download speed on my Windows Vista have dropped from 300kb/s to around 20kb/s. It took me several attempts to find out what the problem was.
It first seemed to me that my ISP was in a technical difficulty state. I am on a dual-boot system with both XP and Vista. In order to verify that Vista was not the cause of the problem, I booted into Xp and did some speed throughput test. Surprisingly my download speed in XP was normal (300kb/s). Clearly the cause for my slow download in Vista was the Vista itself.