This looks vers similar to what happened to my N810 this morning

My machine was working when I went to bed last night but not this morning
Power surge while writing to the file system?
It started out that I got an error message when I tried to open my calendar
The appropriate entries were displayed on my desktop so I knew they were still there
Last night I had deleted the text capture program to clear some space so went into Application Manager to reinstall it so i could capture the error messafe but Application Manager wouldn't show me any programs to install and when I checked it said there were no programs installed on the device either
It sounded like it was time for a reboot so I shut down and restarted
Everything looked normal but as soon as the splash screen displayed and the chimes sounded the screen went black and the reboot sequence started again...and again...and again...

What worked for me
I pulled the battery and went to lunch
When I got back I put the battery back in and powered it on
The Nokia screen came on but there was no progress bar
I think I saw the hands and heard the chimes but I know it looped back and this time booted normally
I poked around and found that my memory, which I knew was low, was down to 1KB free after the overnight emails
I used file manager to delete all my saved maps and that got me enough breathing room that my calendar started working and Application Manager would display items installed or available for installation
I deleted everything I had installed that wasn't essential and with ~50MB free I haven't had ant problems since
I just checked and my boot is still normal