Hello, I have installed power-kernel-47 (ondemand max freq 1150) on my Nokia, have used swappolube (applied proposed settings) approx week ago and I have had first crash (reboot) last evening. Phone crashed after some time of Internet surfing (wifi connection) in moment of max. cpu usage. Gui went freeze for sometime and then reboot. BUT it is not seems to be a cpu overheat. Temperature, shown in cpufreqUI was 48-49 *C

Can you give me advice what to do with it?

Maybe this information is not enough? Ask me for details.

P.S. Forgive me my mistakes in English - I'm russian-speaking

Try out with lower frequencies first. Every N900 has its own stable settings so you got to find the most suitable settings for your device. I would suggest for you to try sum frequency <= 850 and juice up to max if and only if needed.