Ran into my first nasty FireFox spyware/adware. Something hijacked my start page in FireFox! Now it points to some non-existent web site.
Spyware isn't just a Microsoft problem and it's not just a matter of IE having more security holes than other products (regardless of what many say) - it's also a matter that MS is the biggest target, they are the biggest barn in the field.
Unfortunately, that comes with the territory. But other browsers need to be wary - as they gain in popularity, security holes will be appearing for them as well.
This is every browser's problem - IE is just one of the biggest (and easiest) targets.
Firefox - Rediscover the web