Hello to all designers out there...
I am new in Inventor 2011, and sometimes when I open a a file or blocks, they become invisible. How can I make it visible?
 
Sugito

zoom ...allit may help

No it dosen't help.
I am sure it kind of invisble mode. But can't get the lines visible.
You never had this problem.
Happens many times I downloads blocks from this Cad Forum. I download, later when I open the files, I can't see anything.

Have you checked to make sure that the components visibilty is turned on?  Or that the component isn't suppressed?