Please follow these instructions carefully!
Download and install APM from: http://www.diamondcs.com.au/index.php?page=apm
Close all windows except HijackThis and fix these lines.
R1 - HKCU\Software\Microsoft\Internet Explorer\Main,Search Bar = file://C:\DOCUME~1\JOHNST~1\LOCALS~1\Temp\sp.html
R1 - HKCU\Software\Microsoft\Internet Explorer\Main,Search Page = file://C:\DOCUME~1\JOHNST~1\LOCALS~1\Temp\sp.html
R1 - HKLM\Software\Microsoft\Internet Explorer\Main,Search Bar = file://C:\DOCUME~1\JOHNST~1\LOCALS~1\Temp\sp.html
R1 - HKLM\Software\Microsoft\Internet Explorer\Main,Search Page = file://C:\DOCUME~1\JOHNST~1\LOCALS~1\Temp\sp.html
R1 - HKCU\Software\Microsoft\Internet Explorer\Search,SearchAssistant = file://C:\DOCUME~1\JOHNST~1\LOCALS~1\Temp\sp.html
R0 - HKLM\Software\Microsoft\Internet Explorer\Search,SearchAssistant = file://C:\DOCUME~1\JOHNST~1\LOCALS~1\Temp\sp.html
R1 - HKCU\Software\Microsoft\Internet Explorer\Main,HomeOldSP = about:blank
R1 - HKLM\Software\Microsoft\Internet Explorer\Main,HomeOldSP = about:blank
O2 - BHO: (no name) - {13C861B2-0082-4B8B-94CC-F0F41BB317AF} - C:\WINDOWS\System32\oebjnab.dll
Then start APM.
In the upper window select explorer.exe
In the lower window find and rightclick the BHO from the HijackThis log
Select Unload DLL and click OK on the prompts that follow.
Reboot and scan with AdAware (check for updates first!) to remove the txt and html protocol association.