@StickYY,

Maybe this is not relevant, but which kernel are you using? are you overclocking? Is SmartReflex enabled? Have you installed speedpatch and/or batterypatch (even if you later uninstalled it), are you using CSSU?

Any other "mods" or "tweaks" that might be worth mentioning?

I realize that if this is not your N900 you may not have an answer to all of that..

I also realize that you state that you have flashed your N900. Are you 100% you flashed it completely? Did you install *anything* after flashing?