Remove Virus in XP that Disables “Show Hidden Files”

Check the registry setting:-

Start>Run>Regedit>OK

Now navigate to:-

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\
Advanced\Folder\Hidden\SHOWALL]

In the right pane the CheckedValue should be 0×00000001(1) and
DefaultValue should be 0×00000002(2).