WOW if VLC can't play it ... then I am suspicious about the file. Or about something with your system settings. Maybe someone else has ideas .. sorry. Tried rebooting? How about defragmenting your drive ... that can make a big difference since video requires fast reading from the hdd. A fragmented HDD slows reading from the drive down, & can slow your whole computer down. Try defragmenting your drives/partitions. Also try moving your file to another partition before opening.