I am afraid that I cannot answer you question in any technical terms, since (as most here know) I am a caveman in that respects; but the same has happend to me in the past on a laptop that my son had had. I just blamed it on the machine rather than the system.
On this present PC, using the very same server and IP address, I have no problems...although in long posts, sometimes I get kicked off, and then sending the post takes some time. Then, when it is posted and the window goes to that post, I can see the post I have just made, but my little 'on-line' circle has a blank X in it...although I had just suceeded in posting.
If one uses the 'preview' button from time to time during a long post, that would not happen, but then you would lose all your paragraphing...and that is a pain to fix.
Well, maybe someone will come along who can fill you in better on what might be the cause, and all. OH...I do want to thank you for posting you question here though. . . in that, I had gotten tired of seeing that 'All Moderators should...' with my user name under it. Thanks for that side help !! MM