Cannot open my "create playlist" on Microsoft Media Player

Clicked on the name of the file and got error
message "Windows Media Player cannot find the specified
file. Be sure the path is typed correctly. If it is, the
file does not exist at the specified location, or the
computer where the file is stored is offline."

The other file names work ok and the settings have not
been touched since we started using the product 18 months
ago.

Here is the error message "help" solution whic I do not
understand.

0xC00D1197: Cannot play the file
Windows Media Player cannot play the file. You may
encounter this error message for one of the following
reasons:

Your computer is not connected to the local area network
(LAN) or to the Internet. Connect to the network or
Internet, and then try again.
The path to the file is not valid. If you typed a Uniform
Resource Locator (URL) in the Open URL dialog box, ensure
that the file name is spelled correctly and the path to
the file is correct, and then try again. If you clicked a
link on a Web page, the link may not be valid.
The server is down or busy. Try again later.
Some network protocols in the Player are not enabled.
Enable all network protocols, and then try again.
The proxy server settings for the Player are not
configured properly. Verify that your proxy settings are
correct, and then try again.
To enable all network protocols
On the Tools menu, click Options, and then click the
Network tab.
In the Streaming protocols area, select all the protocol
check boxes.
To verify your proxy server settings
On the Tools menu, click Options, and then click the
Network tab.
Verify your settings in the Streaming proxy settings
area.
Note

If you do not know what your proxy server settings should
be, on the Network tab, select a protocol, click
Configure, and then select Autodetect proxy settings or
Use proxy settings of the Web browser (available for HTTP
protocol only).
Error ID = 0xC00D1197, Condition ID = 0x00000000

If anyone can help it would be much appreciated.

Thanks

Ben