I've encountered a malware problem for the first time in 25 years of using Macs. i lost my internet connection the other day, and a Google Chrome installer window popped up. Working with my ISP we discovered that the DNS address in my Airport router had been changed to an address in Bulgaria (!). I managed to change it back to the proper address, rebooted the router, and all is good, except the Google Chrome installer window keeps popping up when I try to save TextEdit docs, and when I try to change the file sort (date/size) on my main hard drive. Also, when I switch users or reboot, the screen flashes quickly three times. No other symptoms that I am aware of. All my software is up to date. No other accounts on the computer or network have this problem. I assume this malware made its way onto my computer when the DNS on my router was changed. Not sure how that could have happened since it's password protected and I live out in the country. I've run Avast and it found a bunch of "infected files" all of which I removed. No change. Same with ClamX, no change. I've also zapped the PRAM, ran Disk Utilities, and Disk Warrior. The problem goes away if I: Do a Safe Boot Log in as a different user I've Googled the hell out of this problem, but can find no one with the exact same issues. Does anyone have any idea of what else to try?