Make sure your OSX LW is not using the same port (connection or listening port) as any other program on your computer or network. Your Linksys is port forwarded? It sounds like it. Is your LW set to Manual Port Forward?

Make sure Performance options are all disabled in LW. Make sure OOB is disabled under Speed options. Set LW to connect manually. Let LW open, load any shares or incompletes if any, then try connecting.

Send me a PM, I will send you an older LW version to try out, the newer versions are a little trouble-some connecting.

PS: Sorry I didn't see your thread earlier.