I have a site that has an IE8-only problem:

The code is:

var w = window.open(urlstring, wname, wfeatures, 'false');

The error is:

Message: Invalid argument.

Line: 419
Char: 5

Code: 0

URI: http://HOSTNAME/js_context.js

I have confirmed the line number of the code (the Line and URI are correct), and I understand in later versions of IE8, this is considered accurate.

I have checked all the incoming parameters in the call by dumping alerts, and they all look valid.

This problem does not happen on FF (probably 3).

UPDATE:

The problem appears to be in using assigning the result of window.open() when doing var w. When I split the line into two statements it works in IE8.

UPDATE2:

Based on:

http://javascript.crockford.com/code.html

When a function is to be invoked
immediately, the entire invocation
expression should be wrapped in parens
so that it is clear that the value
being produced is the result of the
function and not the function itself.

This is not exactly what is going on here, but I found that applying the principle solved the problem, in IE8's compatability mode.

var w = (window.open(urlstring, wname, wfeatures, false));