You mean LWO right? I don't know what an IWO file is....if it's an LWO (Light Wave Object) file, then it should import fine unless it's corrupted. If it's corrupted or your PC is out of memory/having other issues, you may be out of luck...

What is the error?

 My Rendo-Space 
Do you know where your towel is?! I love Vogon Poetry. :P
DON'T PANIC!

Portland Pirate Festival Arrrr!