The application was probably fit into a smaller size package for faster downloading using a compression application such as Zip. There are many different compression schemes and yours had problems. Maybe it didn't know how to handle the file, or perhaps the file was corrupted during downloading. Try downloading the file again. You can also right click on a file's link to do the download and place it on your computer so you can do the decompressing separately by double clicking on it. If you still have problems then post the file extension here, the 3 letters after the dot at the end of the file name, e.g. .zip., .sit, etc.