Sorry to dig up an hold post but I'm having this same problem.
I'm running CM7 on a Droid X and have a 6+gb tombstone file that is hogging all of my internal memory.
I'm able to locate the file through file explorer but when I long press the file and select delete it begins to delete the file then comes back with the message, "This file cannot be deleted."
My guess is some program is actively writing in this log but I can't figure it out.
Any help here?
Any way to delete this file from Clockwork recovery before the phone boots up?
Any help would be great, right now I can't sync my email which is a big problem.