This looks like a different N900 reboot problem from the ones everyone has been talking about. This is what I get:

I had this problem on two different N900's, both after installing the upgrade to Maemo 5 PR1.2, and after installing some basic apps (vim, Battery Eye, CuteExplorer, Tweakr, ShortcutD, Conversation Widget, and a few more).

In the first case, the phone became less and less responsive. I would tap on some button, and it would take 10 to 30 seconds for there to be a response. (I would put the phone back in the holder, and then the next time I took it out it would have responded.) I wanted to reset the device, so I took out the battery and then put it back in.

In the second case (today), the phone had been behaving normally. Then, once, when I took out the phone, the screen was blank and wouldn't turn on. Again, I took out the battery and then put it back in.

In both cases, after I hold the power button to turn on, I get the Nokia logo, and then the flashing 5 dots flashing back and forth. That is all that happens. In the first case, I even left the phone on for hours, but it stays stuck with the 5 dots flashing back and forth.

I called Nokia in the first case, and they told me to send the phone back for repair, but since it was within the return period for the store, I went back to the electronics store and exchanged it for another one. This time, I don't know what I'll do. I need to decide if I want to return it and not get any N900 at all.

Is there a way to break out of this hung reset condition? Is there a reset button I can poke through a hole? Can I save my N900?

Any help would be much appreciated. This seems different from the "keeps rebooting again and again" problem people have been posting about.