OK that's an age old problem with Java, Mac classic & LW. You should still be able to drag& drop the files onto StuffIt Expander. If not, check how long the file name is. If it's very long then shorten it. OS 9 only allows 31 characters in the file name. With your file names the .sit might also have been lost. Put .sit at the end of the name (be sure it is a SIT file.)
Another few solutions: See these 2 threads:
http://www.gnutellaforums.com/showth...threadid=33720 http://www.gnutellaforums.com/showth...threadid=32574