Run both Adaware and Spybot Search and Destroy from safe mode, updating each program before you scan and setting both to fix what they find.
*AdAware SE: http://www.lavasoftusa.com/software/adaware/
*Spybot S&D: http://www.safer-networking.org/en/index.html
After doing that I suggest you post a HijackThis log for assistance with your problem.
Your mention of about:blank and freeweb pages shows that you do have an infection.
Read the pinned post in the HijackThis forum, here Carefully read and follow all directions explicitly.
Following instructions run a log, and post it in the appropriate HJT forum, at this link
. Do not attempt to fix anything by yourself using Hijack This yet.
A member of the HJT Team will analyze the log, make recommendations and offer assistance.
It may take a period of time to get a response to the log you posted because the members of the HJT Team are kept very busy. Please
be patient as this team is manned by volunteers. They will help you as soon as possible.NOTE
Once you have posted your HJT log, please DO NOT make any additional posts in the HJT forum until you get a response from a member of the HJT expert team.
The first criteria they have when looking for logs that need replies are posts showing 0 replies
. If you make an additional post, it will show as having 1 reply
A team member, looking to see if a reply has been made might well assume another HJT Team member is already assisting you and might not open the thread to respond.
So, make your post and wait for a response from a team member.