Yes about:blank is very difficult to remove.
First, do a deep
system scan, if that does not find and remove it, boot
your system into safe mode.
Start>Run> (type MSCONFIG)>Go to the Boot.ini tab. Under
Boot Options put a check next to /SAFEBOOT.
Reboot the computer, and log in as the admin.
Run the MSAS Beta1 with a Deep System Scan, reboot, and
run it again, continue this until MSAS does not find any
problems.
Once it comes up clean go to MSCONFIG again
Start>Run> (type MSCONFIG)>Go to the Boot.ini tab. Under
Boot Options take the check out of /SAFEBOOT.
Reboot your system into normal mode, open the MSAS and
click on Advanced Tools, Browser Hijacker Recovery, click
Check All, and Restore.
Next Click on Advanced Tools, Click on System Explorers,
to go IE Toolbars, anything that does not have a star,
block, then go to IE BHO's and do the same.
Go down to the Windows Hosts File, and the first one
should be 127.0.0.1 Local Host, if there is anything else
there remove it.
That should solve your problem.