I had problem of N900 rebooting endlessly.

By taking the battery out, putting it back and when the device was shutdown connecting usb while holding u from they keyboard i got to the "usb mode".

Biggest problem was that i just couldn't get my N900 reflashed with Vista 64-bit. Tried enabling unsigned drivers(that's not that easy anymore with SP2) and what not. In the end i throwed the device to my friend who got Ubuntu in his computer and all was ready in 3 minutes.

I would expect the same from all 32-bits.