I only find them after a powershell window that flashes up if i run a scan after i find them.
The powershell install apears to be on a timer of some sort as the last few tiems its come back has alwasy been at 23:11, MWB also then stops an out going website conection i assume is related.
To compleate the removal I restart the PC and normally scan again, (when i find nothing) it then tends to come back agian at 23:11 then next day.
Last night i pulled out the ethernet cable at 2300 and closed all browers and it still popped a powershell window, i scanned right away and found it still.
Hope this helps