Msn messenger and 10.5.2 unable to login

Hi, I have this problem with two macs (macmini and macbook intel), both with same version 10.5.2 (and same problem since 10.5.2).

microsoft messsenger (msn) is unable to login (same apply to adium or any other if try to connect to messenger.hotmail.com 1863).

-------------------------

Firewall is disable. You get in the messenger log

2008/05/01 19:40:04.203 Connecting to messenger.hotmail.com (port 1863)

2008/05/01 19:40:04.230 Network thread got exception -3260

2008/05/01 19:40:04.230 >-->> VER 3 MSNP14 MSNP13 CVR0



2008/05/01 19:40:04.231 Connecting to messenger.hotmail.com (port 1863)

2008/05/01 19:40:04.264 Network thread got exception -3260

2008/05/01 19:40:04.264 Login (0) failed with error: (7.0)


-----------------------


I run a TCP dump and you can see the packages go out to the router but you don't get an ACK status, only RST packets return.


Friends not using Leopard is not having problems with the same version of messenger 7.0 (and earliers).

Problem persists even if in other network (macbook connected to different networks and wireless) so problem is not in the router or ISP.

Is there anything that leopard might be blocking (or broke)..., running "dscacheutil -flushcache" doesn't help and nothing is blocking connections to that port as well as DNS is resolving fine to the right IP for messenger.hotmail.com.


Any one can give me a hint what could I try (without re-installing leopard)?


Any new ideas I could try to resolve the problem?


Thanks in advance