Podge asked me peek in, since I have some experience with this kind of problems. Occassionally it happens to me too that I lose the content of my post when submitting it. It happens very rarely (max. couple of times per year - and I post frequently as you can see). Usually it is due to connectivity problems. However I never got prompted to log in again, so the problem in this case may be different than the connectivity.
One possibility that comes to the mind is some cookie blocker software (most anti-virus software have such opiton), but then it is strange that it does not happen more frequently. Another possibility may be that between loading the page and submitting it, your IP address has changed (that happens at most people, since IP addresses are often assigned dynamically and renewed regularly). I think that normally it should not matter, since the cookie would assure identifying you anyway, but if it is blocked somehow, it may be the clue.
If you have a dynamic IP, you could run a test by intentionally resetting the router (to get a new IP address) just before submitting a written message - if you can reproduce the unitnetnional logging off, then we have localized the problem. If you want to test it do it in this way:
- note your IP address (see it for example at www.whatsmyip.org)
- load a DB page, type a message
- power off your rooter, wait a few seconds, and then power it on again
- verify your IP address again. If it did not change, try resetting the router again, waiting a bit longer (a few minutes). If it does not help, you may try waiting a few hours or a day (letting your browser with DB open). If you still have the same IP address, it may be a fixed one. In any case write the address down, and the next time you get logged off, verify whether it changed or not.
- submit the prepared message. If you get logged off, it is likely the IP address that caused it. Try repeating the procedure to confirm the theory
It would interesting to know what type and version of browser, OS, and AV software you use - perhaps we could then look it up better.
BTW, since as I wrote it happened to me several times that I lost a written text when submitting it (and due to Murphy's laws it was always quite a long text), I learned to always copy the message (Ctrl-A + Ctrl-C) before submitting or previewing it. Also using the preview frequently at writing the message helps, since you can then go back in the browser history to recover the original text. Unfortunately this does not work directly - when the submission fails and you go one page back, the message is empty. Only if you did a Preview in the meantime, the last preview can be recovered. That's a big disatvantage of the vBulletin forum software. In some other forum applications you can recover the message by simply going back.