These can be pests can't they.
If you are still having problems, please post the search page your home page keeps getting set to.
There are specific fixes for some search sites.
One possibility is that the mal-ware replaced a system file with one that resets your home page on each boot.
Go to the Run box on the start menu.
Type in SFC.
Click Okay.
Restart your PC.
The reboot will take a while as SFC is scanning all of your system files to make sure that they are correct.
Here is the description of SFC from Windows Help Menu:
System File Checker (sfc)Scans and verifies the versions of all protected system files after you restart your computer.
Syntax
sfc [/scannow] [/scanonce] [/scanboot] [/revert] [/purgecache] [/cachesize=x]
Parameters
/scannow
Scans all protected system files immediately.
/scanonce
Scans all protected system files once.
/scanboot
Scans all protected system files every time the computer is restarted.
/revert
Returns the scan to its default operation.
/purgecache
Purges the Windows File Protection file cache and scans all protected system files immediately.
/cachesize=x
Sets the size, in MB, of the Windows File Protection file cache.
/?
Displays help at the command prompt.
Another option is to install a program called Start Page Guard
http://www.spywareinfo.com/downloads/spg/
You might also want to set IE to the highest security settings and disable ActiveX and all install options.
Re-boot and see if you can set and hold your start page.
Any pop-ups or questions might help locate the file that is running to change the start page.
Chas