A friend tells me that almost all of his folders in a partition are now inaccessible.
Sherlock finds them but can't open them.
I don't have many details but apparently, folders with a name starting with A, B, C or D are still there, and others are invisible.
He suspects that this is caused by a virus and wants to buy NortonAntivirus.... is it a good choice? which antivirus should I suggest him?