You have at least one trojan on the system, maybe more. MBA-M should have found those. Update the program and run it again, a Full system scan. Be sure that everything is checked, and click Remove Selected.
Reboot the computer.
Run HiJackThis again and place check marks next to the following if they remain,
O2 - BHO: UrlHelper Class - {74322BF9-DF26-493f-B0DA-6D2FC5E6429E} - C:\Program Files\BearShare Applications\BearShare MediaBar\BearShareIEHelper.dll
O3 - Toolbar: BearShare MediaBar - {D3DEE18F-DB64-4BEB-9FF1-E1F0A5033E4A} - C:\Program Files\BearShare Applications\BearShare MediaBar\BearShareMediaBar.dll
O4 - HKCU\..\Run: [SystemManger] C:\Program Files\Internet Explorer\iexplorer.exe
O4 - HKUS\S-1-5-21-1935655697-1897051121-725345543-500\..\Run: [SystemManger] C:\Program Files\Internet Explorer\iexplorer.exe (User '?')
O13 - DefaultPrefix:
O13 - WWW Prefix:
O13 - Home Prefix:
O13 - Mosaic Prefix:
O13 - FTP Prefix:
O13 - Gopher Prefix:
Click the Fix Checked button. Exit HJT.
Reboot the computer.
Run a new HJT scan and post that log.