Following ckleea's recommended link and their method, I re-compiled Asterisk 1.8.1.1 again. This time, the errors mesage of chan_gtalk and res_jabber are resolved as they disppear from the /var/log/asterisk/messages. What a useful guideline! Thanks.
However, there are still errors loading modules for the res_calendar_icalendar.so and related files. I remember that ckleea C-Hing had said he had some problem on icalendar when compiled his Asterisk 1.8 some months earlier. Is that the same problem as you? Could you advise how it was resolved? Thanks.
Wrong version of library used. You encounter this problem when you upgrade your system too frequently. This is why many stable system do not bother any upgrade. Of course this is not for Microsoft windows based system!