We'll need more information to figure out what's happening, manujuca. However, please start a new thread for this new problem.
If you don't already have a version of aMule with debug information in it, go to
this thread and download aMule-Mac.CVS.2006-01-14.Debug.zip (notice the "Debug" in the name).
Now, open Applications -> Utilities -> Console. It should be showing you the "console.log" file. Press the "Mark" toolbar button with the flag icon to insert a timestamp. Now, run your new aMule and connect, so that it unexpectedly quits. In Console, copy the stuff that was written to the console log after the mark that you inserted and paste it to your new thread.
Now, in the Finder go to Home -> Library -> Logs -> CrashReporter and find amule.crash.log. Attach that file to your post with the stuff from the console.log.