Ciao Cimmo,
are you still using Ubuntu or is this on another operating system/distribution?
Could you please open a new thread in the forum and tell us more about your operating system, library versions and if you use self compiled packages or where you downloaded them? We'll then try some things to find our more about the problem.
As it's very hard to fix such bugs (they are probably not directly caused by aMule, but by an underlying library), your assistance is much appreciated.
Thank you!