OnLoad problem

Hi
 
I have a body onload property that calls a function named init() defined
in a separate javascript file. The first time, the page gets loaded with
the required function, but on re-submitting onto the same page, the body
doesn't get loaded completely giving the error message that the function
init() is not defined. 
 
Is it any problem due to the declaration of the javascript function in a
separate file? Or do we have to declare the function invoked in the
onLoad event inline with the rest of the html code? Does declaring the
javascript source outside the head tag cause problems like these? And
does the presence of frames lead to any problem like this?
Please help.
 
 
Thanks and Regards
Vinoj Vijayan