A: This happens if the system is infected by Virus or other Malware, which modifies the
CheckedValue registry value in these branches:
HKEY_LOCAL_MACHINE \ SOFTWARE \ Microsoft \ Windows \ CurrentVersion \ Explorer \ Advanced \ Folder \ Hidden \ NOHIDDEN
HKEY_LOCAL_MACHINE \ SOFTWARE \ Microsoft \ Windows \ CurrentVersion \ Explorer \ Advanced \ Folder \ Hidden \ SHOWALL
This ploy is used by many Viruses, so that the hidden file (malicious executable or script) won’t be displayed in Explorer. (
REF Google Search Results). Also note that some Viruses remove the above option altogether from the View tab of Folder Options applet.
To fix the above setting, download
foldersettings.reg and save to Desktop. Right-click on the file and choose
Merge. This fix can be applied in
Windows XP as well as in
Windows Vista systems.
Reconfigure the
Show hidden files and folders option now. Then update your anti-virus software and run a full system scan. And don’t forget to
follow-up with a thorough checkup for Malware.