I seem to have harboured some sort of unknown user when I check the properties of certain folders on my external hard drive and click security there appears to be a unknown user for some of these folders. The user is named: S-1-5-21-1659004503-329068152-839522115-1003 I also have a problem with a folder and file when I try to delete them I get the notification: * an unexpected error is keeping you from deleting this file. If you continue to receive this error, you can use the error code to search for help with this problem. 1. Error 0x80070570: The file or directory is corrupted and unreadable 2. Error 0x80070091: The directory is not empty. I need assistance on how to delete this files/folders as well as deleting this mysterious user. I am running Kaspersky Internet Security 2012 and it didn't detect anything. Thanks.