There is a worst one of all, Norton anti virus has got to take the prize. McAfee takes second place and Kaspersky third. This is not to say that they are not good at protecting your computer but it is the other problems that they cause that is the issue.Been using McAfee for years. Nothing more wrong with it than any other Firewall/Anti-virus suite out there. You're just like those morons that flame Firefox without any justifiable reasoning.
Read my message above. I work with dozens of AV suites every day. McAfee and Kaspersky are the two worst culprits for totally screwing systems up. Count yourself lucky for having used it for years without issues.