Class not registered

I installed KM Player on my Windows 7 Ultimate system. When I double click a video file and play it in KM player there is no problem but when I double click on KM Player then the message "Class not registered" comes. When I close the program there is an option to check for solutions in Windows 7, I click on it and it says that flash player needs to be installed. But I have already installed it.
I am sure the installer is not corrupted as I installed it on my Windows XP SP3 system(I use multi-booting) without any problem.
What should I do? Thanks in advance.

try this:

Click on Start > Run... > and type regsvr32 quartz.dll

apparently many have this issue with different players. Found this solution on google, not tried on my own. You need to register this file manually.

Thanks that worked for me also.

Thanks that worked for me also.

Glad i could help buddy