Files Folders Mysteriously Disappearing From Drive?

On Sunday The 25 November 2012 Approximately 11:30pm I Turn Off My Computer And Next Day On Monday The 26 November 2012 Approximately 10:30am Turn On Computer, I Checked My Document And I Realised All Files And Folders Disappeared. The System On My Computer Was Like New Installed No Single File Or Folder And Mozila And Microsoft Word Was Missing Data Did Not Open. I Have Another External USB Hard Drive And It Is Also Fine And Files Are NOT Disappearing From It. After A Lot Off Search On Internet On Public Review I Found My File And Folders On My Computer Was Located In Different Place {Local C - Documents And Settings – Administrator - Administrator's Documents} My Computer System Is Window XP 3 Install, Internal HDD 300GB There Wasn’t Any Fault With My Computer Or Hard Drive And No One Use My Computer Except Me And I Have Antivirus Installed {Norton} My Advice, If Your Files Or Folder Are Disappeared “DO NOT” Reinstall Your Computer System. First View Public Review And Check Your Computer If There Is Chance To Resolve Issue And If There Is No Hope Then Reinstall New Systems. Check Your System: Go To The Control Panel, Appearance And Personalization, Folder Options, Show Hidden Files And Folders, And Then The “Appdata” Folder Will Show Up. {Local C - Documents And Settings – Administrator - Administrator's Documents} C:\Users\Username\Appdata\Local\Virtualstore If The Files Had Actually Disappeared Or Had Just Become Invisible Because Of Some Permissions Problem. Could A Hacker Have Gotten Into My System? Entered Himself As A User (Unknown User). They Go Into The System As Admin. They Could Change Permissions, Make Files As Hidden And Removed Admin Permissions To Access Them. Here Are Some Tips: • The File And Folder Disappearance Could Be SOMETHING/SOMEONE Is Making Changing Or To Disappear Documents. • Make Sure Drive Is NOT Being Shared On The Network. • Ran Scan Disk And There Is No Errors On Computer • Run Anti Virus And Spy Ware Good Luck