I get this,

clicking 'no' means the page displays flawlessly.

it's refering to this part of jquery1.4.2.js:

// Get the Nth element in the matched element set OR
// Get the whole matched element set as a clean array
get: function( num ) {
    return num == null ?

        // Return a 'clean' array
        this.toArray() :

        // Return just the object
        ( num < 0 ? this.slice(num)[ 0 ] : this[ num ] );
},

I assume i'm calling something in the wrong context somewhere in one of my js files (which would be a real mission to find).

Will standard IE8 users get this error?

(i imagine ms make it pretty difficult to reinstall ie!)