On Windows XP with Firefox 7.0.1, after clearing the cache the message stating the hdd space used by the cache disappears. Even after browsing for a short while the and returning to the options dialog the message is still missing. By contrast, on OSX, the message states that I am using 0 bytes immediately after clearing the cache. The message is also visible after returning to the preferences dialog on OSX. "Your cache is currently using 0 bytes of disk space" Even after restarting Firefox the cache message is still missing.
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