This is boot helper or boot mode. This mode is there to help one upgrade IOS on run-from-flash devices. You can get to this mode in one of two ways. Either your main IOS image is missing or damaged, or the config-register has been set to something like 0x2101. Do a show ver. If you see the config register is set to anything other than 0x2102, enter config mode, and do:
config-register 0x2102
Then exit config mode and reload. Do not save the config. If all goes well, you should reboot from the main IOS image in flash.