Problem assigning material to object (perhaps because of block instance?) please help!

Hi there,

I am trying to make renderings from a file i was given but there are certain objects that won’t render, they just turn out black. It seems like they were all given a texture, which was linked to a file on the computer from whence they came, so I tried unchecking the texture box in object properties and then allocating a new material from toucan, but that didn’t work. I also just tried changing the material properties. Nothing seems to work. I noticed that the object type is “block instance”…could this be the problem? If so, can someone please tell how to go about undoing the block instance? any other suggestions welcome too !