I’m upgrading from Firefox 0.x to 2.x on one of my computers. Decompressing the downloaded file seemed to be taking far too long, so I took a look at what was up. Somehow, it seems that the incomplete download of 2.4MB (the whole thing should be around 9MB) managed to cause gzip to write out 521MB of data before I stopped it.
The moral of the story? Always check the MD5 sums.