Here's the problem - Internet Explorer seems to have decided that the home page About:blank is what will greet you every time you open a new browser window. You try to change it back but either your Internet Options are greyed out or you change the page back, only to find next time you start Internet Explorer the dreaded About:blank has returned.
There are many possible causes for this behaviour and most are evil. One possible cause is a virus, but this is not very common. The most likely culprit is an adware/browser hijack program - in particular, CoolWebSearch.
The symptom that identifies the CoolWebSearch or a close variation is that About:Blank appears as the address, but in the background a window pops up stating that spyware, adware or something similar has been found on your system. CoolWebSearch is a browser hijack program - it that takes over your page, and keeps changing it back. It's purpose is to show you advertising, or flog you an over-priced piece of software to fix the issue CoolWebSearch has created. The About:Blank change is a trick designed to confuse users - regrettably, it is very successful!