How to delete these threats

Hi

I was reading on the internet that last.exe and updateloader.exe are threats. So, how to remove these files without affecting the rest of the system? The first .exe file is in C:\Documents and Settings\Computer\Local Settings\Application Data\Xenocode\Sandbox\COMODO \4.00.0002\2010.11.27T19.25\Virtual\STUBEXE\@APPDATA@ I am not able to delete it. The license of my KAV was finished so i installed the latest version and it was also not able to delete this file.

Thanks