virus

yes, it's a trojan...follow this link, it should help:

*www.liutilities.com/products/wintaskspro/processlibrary/isass/

try deleting the file and c if it helps....if it shows up on ur trojan scanner, then try 2 fix it frm there...

It's name is TROJ_ISAPASS.A. You can find more info here.
*www.trendmicro.com/vinfo/virusencyclo/default5.asp?VName=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...
*www.thinkdigit.com/forum/viewtopic.php?t=15729