It happened to me a few times already - one moment I find myself unable to talk in the chat and I can't see the chat, and everything looks just as if I my connection was going to get timed out, but it doesn't. I can fly all over the sector I'm in for as long as I want, yet I don't show on the active players list. Fortunately the /verbose 8 command worked and here's what it gave out:

[06/02/04 09:17:57] seq 49 duplicated - dropping
[06/02/04 09:18:00] resending seq 229
[06/02/04 09:18:00] resending seq 230
[06/02/04 09:18:00] seq 47 duplicated - dropping
[06/02/04 09:18:01] resending seq 231
[06/02/04 09:18:01] seq 48 duplicated - dropping
[06/02/04 09:18:01] seq 49 duplicated - dropping
[06/02/04 09:18:03] resending seq 229
[06/02/04 09:18:03] resending seq 230
[06/02/04 09:18:04] seq 47 duplicated - dropping
[06/02/04 09:18:04] resending seq 231
[06/02/04 09:18:04] seq 48 duplicated - dropping
[06/02/04 09:18:04] seq 49 duplicated - dropping
[06/02/04 09:18:06] resending seq 229
[06/02/04 09:18:07] resending seq 230
[06/02/04 09:18:07] resending seq 231
[06/02/04 09:18:10] resending seq 229
[06/02/04 09:18:10] resending seq 230
[06/02/04 09:18:11] resending seq 231
[06/02/04 09:18:14] resending seq 229
[06/02/04 09:18:14] resending seq 230
[06/02/04 09:18:14] resending seq 231
[06/02/04 09:18:17] resending seq 229
[06/02/04 09:18:18] resending seq 230
[06/02/04 09:18:18] resending seq 231

and it kept on generating these messages about resending all the time until I logged off. Any ideas what can be causing it?

It looks like your client lost sync with the server and kept trying to reestablish contact.

any idea what your ping was at the time?

It couldn't have been high, I was crossing s10 then and there was only 1 person besides me there. The last I checked my ping before that incident it was around 200 on average and around 500 max, which is pretty normal for me.

It looks like a temporary network outage to me. Packets sent from you to the server were being lost, but you were still getting retransmissions from the server, so your client stayed online but the server gave up. The number of people in the sector doesn't necssarily have anything to do with ping.

Actually it may. On most other online games things are fine at the moment, then someone with a bad connection connects to the server and the lag spreads to all other players. Or just a few.