I have recently used my portable version of Firefox on another computer which already had Firefox on it's HDD. The computer I used also had AVG Free AntiVirus installed on it with AVG Security Toolbar installed on it.
When I started Firefox portable from my USB key, The AVG security toolbar was installed on my version of Firefox portable. But when I went back to my home machine, the toolbar was no longer there.
Why did this toolbar install when it was not installed already. And if that happens, how do I know that my personal information from my FFOX portable was not left on the machine I used?
AVG exhibits this bad behavior. It auto-installs itself into any copy of Firefox that you run on the PC without asking your permission (which isn't very nice). Nothing was left behind.
Sometimes, the impossible can become possible, if you're awesome!