These messages are caused by the improper use of the boot system command.
To specify an image for the router to use when booting, use the boot system flash:[filename] syntax.
Note: There are no spaces in flash:[filename] to specify the filename of the Cisco IOS image to be loaded, as shown in this example:
Router(config)# boot system flash:c3640-is-mz.122-12a.bin
For more information on the use of this command, refer to CFR Commands: absolute - clock timezone.