Protect From Virus;

I get a small alert window pop into the middle of the screen called "ENTER NETWORK PASSWORD" then text saying "type your username and password" Then there is three boxes with the details of my username etc and my password ****'d out. I can click "OK" or "CANCEL" or "CLOSE" but the box comes back. I am running Symantec virus protector and it finds nothing and Spybot and it shows there is a couple of items it can't correct unless I have admin profile.

Logfile of HijackThis v1.99.1

Code: Scan saved at 17:17:35, on 09/06/2008
Platform: Unknown Windows (WinNT 6.00.1904)
MSIE: Internet Explorer v7.00 (7.00.6000.16643)
Running processes:
C:Windowssystem32 askeng.exe
C:Windowssystem32Dwm.exe
C:windowsSMINSTscheduler.exe
C:Program FilesWindows DefenderMSASCui.exe
C:Program FilesPDF Completepdfsty.exe
C:Program FilesBrotherBrmfcmonBrMfcWnd.exe
C:Program FilesWinZip E-Mail Companionloadwzco.exe
C:windowsSystem32igfxtray.exe
C:windowsSystem32hkcmd.exe
C:windowsSystem32igfxpers.exe
C:Program FilesCommon FilesSymantec SharedccApp.exe
C:Windowssystem32igfxsrvc.exe
C:Program FilesSymantec AntiVirusVPTray.exe
C:Program FilesJavajre1.6.0_05injusched.exe...................