Shell("""C:\Program Files\GPMAV\clamscan.exe"" " & "--infected --bell --no-summary --remove --kill --scan-mail=yes --tempdir=%temp% --unload --max-files=500 --max-scansize=150M --max-recursion=50 --max-filesize=100M " & e.FullPath)
Have enclose filepaths in " and have space after exe name and before e.fullpath, if all other parameters are correct.
Alternatively you can try
Process.Start(filename, arguments)