Unexpected error on reboot in UNIX

Hi all,
My remote unix machine failed unexpectly, and I am unable to login to it.

Here is what I can see on the screen -

> Boot device: .... File and args: -i 
> Boot load failed. 
> The file just loaded does not appear to be executable. 
> {1} ok

How can I fix this problem? Has anyone faced similar problem? What could cause such a failure?

Thank you.

try to use "boot -sv" and maybe post the output. also the output of "printenv" and "devalias" would be usefull for troubleshooting.