Another vote for Netscape.
I don't know if it is because Netscape is the program I use most, consequently it generates the most problem, but I have to wipe every file that has the word netscape off my computer two or three times a year.
I barely use IE, and I never use Out(virus_bait)look and they never crash on me when I use them for whatever reason. So that leads me to believe on the heavy use theory.
There is another program that drives me up the wall, it's called "black widow". It's great when it works, but I never know when it will work.