this is possible virus from an infected flashdisk that avast didnt recognize as a threat
what it does :
- hides all your files in the flashdisk, leaving just a shortcut with <your_flashdisk_name_here>.lnk that targets %SystemRoot%\system32\rundll32.exe \\\\{E5500DA0-2A27-481B-9D16-AD532A4DDBE0}.{5B0FCBB8-20D5-4BDA-9D74-A8463B576644},YmlVUTSCBA9NMLKa
*hidden files cannot be shown through folder options, i personally unhide them with a usb antivirus - if you open that shorcut, it will infect your pc with that thing, making every flashdisk attached on your pc do the things above
- oftenly you cant access all your hidden files on the flashdisk
http://www.4shared.com/file/wQ5jRCDYce/E5500DA0-2A27-481B-9D16-AD532A.html
http://www.4shared.com/file/pYZJ5-Zvba/IndexerVolumeGuid.html
my pc is not infected, just hoping avast could improve it’s service with this
this thing is just annoying when you dont have a usb antivirus, you cant access the files, hope that avast can solve this thing in the future 
**i submitted that to avast lab, just explaining here with more details