I have been trying to send a new image out to a cisco 7204 router. The TFTP transfer starts and then fails. the flash size is 24M the file is c7200-is-mz.124-13a.bin file size 23,839. I thought may be the file size was causing the problem so I tried to get the router to boot from my tftp server, the tftp transfer starts and then fails.
Could you post a show flash ?
How about using ftp insted of tftp?
And if you want to boot from tftp I think you need to change the config register.