[Serusers] Windows Messenger and SER

I'm testing SER with Windows Messenger 4.7 and I have problems with the presence service. Those contacts connected when the user connects, appear as connected (correct). But when another contact connects, it keeps appearing as disconnected, and after a long time (more or less one minute) shows the contact as connected. On the other hand, all the contacts appear as disconnected with Windows Messenger 5.1, independently that the contact is previously connected or connects later. Has someone problems with windows messenger?. I've checked that these contacts are connected in SER with "serctl ul show". So I imagine that it's some type of incompatibility with windows messenger.