Other:W32/Zone.Identifier is a stream generated by Microsoft Internet Explorer and Outlook when saving files to the local disk from different security zones. It is not a malicious program.
We do get occasional enquiries about this issue as many Windows XP files have an invisible stream by this name. The typical content of such file would be:
Existence of Zone.Identifier stream on some files is normal, and as such is of not a cause for concern.