automatic shutdown

My operating system is Windows 2000 Professional. When I click on a video or movie link, the Windows Media Player logo appears on the screen and seconds later my PC automatically shuts down, restarts and then begins a check of my C: drive. The message reads: “Checking File System on C:. Some of your disks need to be checked for consistency. You may cancel the disk check, but it is strongly recommended that you continue. Windows will now check the disk. Windows is now verifying files and folders.” After the check is completed the PC starts. If I click on a movie or video link and it is played using Real Player, I do not have a problem.