My Standard Shield is set on "Normal" setting.
Go to Faffy's link he posted and try downloading the eicar.zip files and see what results you get.
The normal sensitivity could react like you are seeing.Please, use the HIGH. Alwil team will change the normal to high and the high to 'higher' in the new versions by default.
You can add to your Standard Shield settings:
On open: WS?,VBS,VBE,JS,JSE,HTA,WSF,WSH,SHS,SHB,HTM*
Created and modified files: ACE,ARC,ARJ,BZIP2,CAB,COM,GZIP,PST,RAR,TAR,ZIP,ZOO,ECE