I have that problem on my Mac and I need to use Stuffit free version to open it instead of the default Archive utility. On Windows I have not run into that problem... Valerie On Apr 4, 2011, at 3:36 PM, Kenny Peyatt wrote: > Hi list this is kenny. I downloaded a book entitled Can America survive? by > john hagee. I downloaded it twice and it tells me that the format is invalid. > I wonder why windows has problem with zip files? I wonder if another copy of > this book can be submitted. Because every time I redownload the zip file it > tells me that it is invalid when I go to unzip the file.