No problem with the latest versions of Firefox and Norton Antivirus 2010.
Note: I'm only using plain old Norton "Antivirus", which sits quietly and does it's job, but doesn't interfere with any operations or cpu performance. I am NOT using the "Norton Internet Security" package, or whatever it's called these days.
The Internet Security suites are pains in the ass, and cause a lot of problems.
I'm a computer technician, and I see people's computers have lots of trouble with these security software packages because the default settings are designed to annoy the crap out of you.
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