Hi,
Did not really want to open a new topic but wasn't sure how else to send this to you... First off, Firebug is amazing, so I just wanted to contribute if you think this is worth mentioning.
For Joomla CMS users, another answer to the question quoted below from the FAQ Q&A may apply to them. If it's not too CMS-centric, it might be worth mentioning that in some popular Joomla templates the user may choose to compress CSS from a System section of the template manager (as opposed to the CMS system configuration). No doubt other CMS templates have similar capabilities.
Q: Why do the source links inside the Style side panel not refer to my CSS file?
In particular, if you are a CMS user seeing files with names of the format long_numeric_string.css instead of name_of_my_actual_style_file.css in the Style panel, check your template configuration for CSS compression. If you see the same type of long numeric string names in Firefox and Chrome for your site but not for another site like the Firebug site then you can be pretty sure its not a Firefox profile issue.