|There is still something trying to launch the trojan at startup.|
It could be something as simple as Windows prefetch.
That is a folder created by windows to access frequently used progs/files at startup.
It is safe to delete the entire contents of the prefetch folder and allow windows to rebuild it.
If that does not resolve the issue you may still have something in the MSCONFIG start list that is trying to launch the nasty, or another hidden part of the infection which needs removal. Antivirus is not the only defence you need these days.
Goin' Fishin' (Some day)