I was watching a film on mine and it paused and I hade to hold in the power button to shut it off.
When I restarted it I get that error message too.
I did the same as everyone else with no luck, so I left it on thinking that maybe running the battery down and charging it again might help but no luck.
I left it for a week then decided to have another go at fixing it.
I removed the battery and used the reset button to set it to factory defaults.
I powered it up and got the error message and tried the USB cable again (Can't remember for sure if it was on or off when I connected it) and I got the option of connecting to my PC and copying a system update to it.
I downloaded the update and copied it to the harddrive and it then updated itself and restarted.
It booted up ok but when I restarted it I get the error message again.
I redid the first bit again and using the XP Disc Management I removed the partition, then redone it.
I restarted the 604 and formatted the harddrive and copied the update and it updated and restarted again.
The pointer needs to be calabrated again on it to work but it's back to normal now and working great.
I set everything up and copied all the folders into a folder on my PC so if it happens again I just need to fix the harddrive and copy the files over.