It's name is
TROJ_ISAPASS.A. You can find more info here.
http://www.trendmicro.com/vinfo/viru...TROJ_ISAPASS.A
Delete these files, if you find them:-
ISASS.EXE
MSSVCHST.DLL
MSHLPAPI.DLL
Since, this trojan creates Registry Entry, it should be removed, so post the log file of HijackThis.
To know how to use HijackThis, see here...
http://www.thinkdigit.com/forum/viewtopic.php?t=15729