virous or trojan

Hi dears
In our network we have a manageable Symantec antivirus that updates every day bat in some of clients we see some Virus or Trojan. this virus changes Folders attribute to hidden and makes a Exe file with same folder name that has an Icon like Folder Icon with a shadow when user click on the shadow folder icon he or she see an error . Kaspersky antivirus can find “Win32.delf.yh and remove it but hidden attrib in infected folders was disable and we can not change them. Could you please help us?
Regards