These wiles were on my NAS the other day and suddenly they became size 0.  Also, I noticed that many files on the Root and folders on the Root were moved to the re-cycle bin.

I have a Synology NAS the contains these files.  I have several Win 7 Ultimate computers with AVAST attached to this NAS.  AVAST could not help.

I have read about some sort of malware that makes these size zero and puts their contents into hidden files but I have not found any solution or further clarification.

Any ideas or help would be appreciated.  Thanks in advance.