Why Are Our Wii Games Playing Poorly Now?

A couple of weeks ago we started playing super smash brothers brawl on the wii. Now when we put any disc in, the picture is terrible, there are stripes running through the picture and it is unclear. Do we need to clean the lens? Is there a way to fix this? Any help would be appreciated!

Suggestion:

maybe your wii has the disk error problem,i hope not though