There's a scary new Windows vulnerability discussed at:
http://www.techworld.com/security/ne...fm?NewsID=2865
http://news.com.com/Chinese+firm+fin...3-5502534.html
A simple image downloaded from a browser could exploit the flaw. This could be done via someone's signature, for example, even if you use Firefox or Mozilla.
To protect yourself, short of surfing with images off (or abandoning Windows), one can adjust the settings in Mozilla or Firefox to allow images only that originate from the same server as you visited.
1) Firefox: Tools --> Options --> Web Features --> check the box for "for the originating web site only" under "Load Images" (you can add exceptions too, for trusted sites)
2) Mozilla: Edit --> Preferences --> Privacy & Security --> Images --> choose "Accept Images that come from the originating server only"
This means you won't see many signatures or images posted within the forum, but you'll be a lot safer. On the upside, the pages will load faster.
