The about:blank page is a good indication of malware/spyware that's been installed. Usually from not reading carefully enough the small print and the box's that have been ticked of the pop up box from some piece of software you installed. They sneak that stuff in all the time.
You need to run your AV and any malware, spyware you have, doing full scans. Also check in the add/remove programs list for any software that might look suspicious and uninstall it. I suggest Malwarebytes, SuperAntispyware, Spybot S&D 1.6.2 for malware/spyware removal.