I have successfully downloaded files from Limewire but when I double click to open them or drag them over the "Stuffit Expander" icon, I get a message that reads "The file blah blah blah.sit does not appear to be compressed or encoded. The application "LimeWire might be able to open this file. Would you like to try opening the file using "LimeWire"? If the file does not open correctly it is advised that you obtain further information about the contents of this file from the sender or provider of the file."

Any idea as to what the problem could be? I'm in Mac OS 9.2.2 and the files I'm trying to open are .sits or .dmgs (which I will open in OSX).