.sit files will not run
 

.sit files fill not run when I unzip them. Messages include: InstallerModeController: No lock file present.
Extractor Directory Not Found, using 'user.dir'
Default properties location.
And: there is no application specified to open the document.
OK I am new to macs, so probably doing something windowlike that is wrong. When the file is completely downloaded I hit "launch" the unzipper program launches and unpacks the file. There are no icons other than a doc. file. When I click these docs I get the above mentioned error messages.
Any ideas?
Thanks

The best way to decompress files is to drag them directly over Stuffit Expander. I suggest you do the following:

1. Do a search for Stuffit Expander in Sherlock (Command F). I'd suggest you download the latest version (7) if you don't have it.

2. Command click its icon and put an alias on the desktop or in the Dock

3. Put a copy of your shared folder on the desktop as well (Applications>Limewire>Shared by default or do a Sherlock search)

Then whenever you want to unstuff a file go to the Finder, open your Shared folder and drag the icon over Stuffit Expander. If it's a valid, uncorrupted file, it should now decompress correctly.