M$ & IE
With the open source browsers there are numerous people working on bug fixes so they get fixed faster. With IE though it is all insular & any bugs are slow to be fixed. "Firefox, Opera, Safari, Sea Monkey, Netscape" a multitude of alternatives if you are willing to take the time to try them.
I think the majority are still IE users only due to the fact it comes pre installed with all M$ installed PC's. They managed to kill off Netscape in the 90's by dominating the market with this business method & it has taken a long time for the third party players to break the grip of IE.
I use Firefox as I prefer how it operates not because of the security.