Reboot into safe mode following the instructions here & navigate to & delete the following:
c:\windows\TEMP< folder contents
C:\WINDOWS\SYSTEM\CKNP.DLL< file
In order to view these files you may have to select 'show hidden files/folders.' Instructions on how to here.
Close all (browser) windows & rescan with hijackthis. When the scan is finished place a check in the box to the left of the following entries & click 'fix checked' :
R1 - HKCU\Software\Microsoft\Internet Explorer\Main,Search Bar = file://c:\windows\TEMP\sp.html
R1 - HKCU\Software\Microsoft\Internet Explorer\Main,Search Page = file://c:\windows\TEMP\sp.html
R0 - HKCU\Software\Microsoft\Internet Explorer\Main,Start Page = about:blank
R1 - HKCU\Software\Microsoft\Internet Explorer\Search,SearchAssistant = file://c:\windows\TEMP\sp.html
R0 - HKLM\Software\Microsoft\Internet Explorer\Main,Start Page = about:blank
R1 - HKLM\Software\Microsoft\Internet Explorer\Main,Search Bar = file://c:\windows\TEMP\sp.html
R1 - HKLM\Software\Microsoft\Internet Explorer\Main,Search Page = file://c:\windows\TEMP\sp.html
R0 - HKLM\Software\Microsoft\Internet Explorer\Search,SearchAssistant = file://c:\windows\TEMP\sp.html
R1 - HKCU\Software\Microsoft\Internet Explorer\Main,HomeOldSP = about:blank
O2 - BHO: (no name) - {AF768ECA-C6C1-11D8-B787-00B03A5FD05C} - C:\WINDOWS\SYSTEM\CKNP.DLL
O13 - WWW. Prefix: http://
Reboot normally after doing the above then post a fresh log plz.