I tried every search in the registry for C:documents and found nothing. Then msconfig to check startup programs and processes, nothing. Autoruns gave more detail but still nothing that remotely looked like the culprit until I knew what to look for..
BTW, Symantec Endpoint found the trojan which apparently put a file called "lsass.exe" in the dir " C:documents and settuingsadministratorapplication data** " and an associated registry entry to run the executable.
I deleted the file/registry entry via Autoruns and that solved the problem. Apparantly Endpoint had deleted everything else that the trojan did but this leftover dialog box at every boot was getting annoying.