He's talking about CPU overclocking. But discard it as a possibility if you didn't overclock it (or if you don't know what it is).
N900 comes with 600mhz as the stock frequency so it shouldn't be a problem.

It's not normal. Mine is stock too and mine last around a day so it's definately some process running in background and draining battery.
Try top in xterminal when it happens again and post the result/screenshot here. As can't say without knowing what process is doing this.

It's not normal, I've never had this happen to me, except where some app I've written has sat at 100% CPU.

It would be interesting to know exactly what is causing your CPU usage mind you.

same problem here. I ran an upgrade using the nokia package manager (don't know which packages were updated), and before finishing all packages I see a reboot happening, and on the white Nokia screen I see a message that it's upgrading something (prob. flashing). Then, after a while the icons on the desktop stopped responding, which happens also some time after rebooting the phone.

Now, I have removed all widgets from my desktop, and the unresponsive icons problem is gone, but the phone still runs through its battery much faster than before, even though no process in 'top' shows large % of CPU use..

I have had no time yet to check which packages got updated. what I did see is that dpkg.log is empty.

Any hints on what to check for in syslog?

Iirc there was a cron script somewhere on the forum (or you could just write one easily enough) which would record the output of ps every now and again. That would give you some indication of what's running when it shouldn't be.

rebooting is the only work around for me

maybe one should have an autokill-runaway-process-deamon like they have in Villainrom for Android... or make the n900 vibrate or bipe if it starts to get too warm

post the result of top here when your cpu usage is high and then we can do something about it. Most likely it will be hildon.

I got the same problem recently, may be about a week, as I see most of the people posting here got this problem last 1-2 months, so obviously it is something with an update of an app and unfortunatelly I do not know what I recently uptated as well. It heats up when when I connect to wifi and start using the internet, after a little the internet dies but it shows that I am still connected to the network, the battery dies shortly after. Only reboot fix is it. When I am not connected to internet the phone is working fine. Any ideas now what I can do...??? Really need to do something cause I bought the phone becuase of Skype and so without internet it is just useless for me...

even i experience the same.. i am running at a clock spped of 800mhz.. and my phone switches off in 4hrs.. is my N900 normal?? i dont experience any heating effect but when i use my gprs it comes for 4hrs.. help me pls..N900 is just a box if it doesnt have a net connection.. pls help..