I've actually already (partially) solved this problem, but am posting to find out why on earth it might have happened, and to help anyone else with this problem.
The battery of my
N95 was lasting around 2-3 hours at most, after behaving normally for the 6 or so months I had it. I was overseas in Rome, roaming (so to speak). My home network is 3 Australia.
Now I noticed that the little packet data arrows in the top left hand corner were on all the time, and when I held down the red "hangup" button, the
N95 would ask "End packet data connection Planet 3?" I would say "yes", and then about two seconds later, the packet data arrows would get going again, and the same thing would happen.
So I figured my phone was using all its battery trying to make some kind of packet data connection. It didn't seem to be chewing up all my packet data allowance as far as I could tell, so it was presumably unsuccessful. Maybe, whatever it was trying to do, that was why it kept on trying.
I actually managed to sort this out myself in Rome, by managing to navigate through the settings fast enough to delete the Planet 3 access point before my 2 seconds was up. (It won't delete an access point that's "currently in use"). I had to have a bit of practice to get that fast. I swore a lot. :)
Now the utterly bizarre thing about this is that when I was back in Aus, I sent the phone in for a warranty firmware upgrade and they actually swapped the phone for a new model with updated firmware (due to a broken LED or something). And on the new phone, after a little while, the same thing happened again, and I had to do the same fix.
It doesn't worry me any more, because now that the Planet 3 access point is deleted, the problem is solved. I even recreated a new access point with the same settings, but the problem hasn't recurred. Wacky.
But I would love to know why the hell it was doing this. I had turned off every setting I could think of (email was set to check manually; WLAN disabled; web only "when needed" and "always ask" for access point, GPS wasn't running, MMS was using a different access point or switched off).
Now that I've resolved it I can't reproduce it, so I probably can't answer any troubleshooting questions... but for a start, has anyone else seen this problem?