unable to recognize the format of this file
 

Can some one tell me why I have this problem?

What is the file extension & is it LW or one of your other programs that gives you that message?
If it is a media file such as a video or audio file, then chances are you don't have the codecs to open & play that file; CODECs list for Movies/Audio/ Alternate players / Video help forums/ video-mp3 fixers. For video files, we normally recommend getting VLC as it has built in codecs. :)