Thanks Eddy

Can I just request clarification of your 4th answer?

I want to scan c:\system_volume_information to check that any viruses that used to reside here have gone.

But when I select Folders in AV I just get the standard list!

If I check C:\Partition_1 and then uncheck all the stated folders eventually C:\partition_1 becomes unchecked

If I check C:\Partition_1 and then uncheck all but one empty folder a scan goes ahead but does not check System_Volume_Information nor does it check hidden system files (boot.ini etc)

I must be missing the obvious but some help would be appreciated