I have 8gb kingston datatraveller 100.It used to work perfectly,but recently i plugged it into my friends computer and copied some files from his pc to my pendrive.when i got home and plugged the pendrive,the files were all some kind of weird format,with a square symbol as filename.I couldnt even delete them,so i formatted my pendrive.Now whenever i copy some files to my pendrive,they dont work.if i copy exe files,a command prompt window comes up and closes.if i copy videos,they cant be opened.Help me please,what should i do to restore my pendrives functionality..........