I've done some test on ports 110XX and have come to an interesting discovery. I tested on a single computer with dynamic IP. Tested the same working port. After reconnect (IP changed) stopped working... after some more IP changes it has worked again. So, same OS (windows XP sp2), same ISP, different IP.

Seems those ports has something to do with IP, but I am really curious what can be. My logic stops at this point. Anyone has any explanation?

I have done another test using virtual machine. At the same time, from host computer proxy worked, from virtual computer didn't. After I reconnected the virtual machine (received different IP), proxy started to work in virtual machine too.