Have you ever try to overclock your n900 using maemo-flasher, because i was also having the same problem that you have i just simply flash my n900.

But if you want to overclock your n900 using maemo-flasher,You can do it,you just need to install cssu. I don't know how but it help me to keep overclock my n900 and also when i goto setting and when i see "about product" It show me all the details like: My firmware,mac address etc.

I Hope this will help you