What could block a script, when there's nothing wrong with it?

Hello, again

I've just wasted some hours trying to get a script to execute. It threw an error saying that the 'object wasn't valid' I decided to give up, wen't home, and later at home started up again to see if I could sort it out.

It executed well on the first run.

Same computer. No changes to the script. ESTK was set to InDesign 5, I checked it a million times.

What could cause this to happen? Caches overflowing? "Blocks" between InDesign and ESTK?
The script isn't callng for any URIs or such.

Here's the bit I was having trouble with:

app.activeDocument.groups.everyItem().ungroup();    

app.activeDocument.layers.everyItem().locked = false;

app.activeDocument.pageItems.everyItem().locked = false;

MoveTextFrame();

function MoveTextFrame() {

    var doc = app.activeDocument;

    var stories = doc.stories;

    var STYLE = doc.paragraphStyles.item("Some Style");

    for (var i = stories.length-1; i >= 0; i--) {

        if (stories[i].appliedParagraphStyle == STYLE && stories[i].paragraphs[0].parentTextFrames[0].parentPage.name == 1) stories[i].paragraphs[0].parentTextFrames[0].geometricBounds = ([38.8, 15, 48.249, 130]);  

        if (stories[i].appliedParagraphStyle == STYLE && stories[i].paragraphs[0].parentTextFrames[0].parentPage.name == 2) stories[i].paragraphs[0].parentTextFrames[0].geometricBounds = ([9.2, 15, 18.6, 130]);               

        if (stories[i].appliedParagraphStyle == STYLE && stories[i].paragraphs[0].parentTextFrames[0].parentPage.name == 3 && app.activeDocument.documentPreferences.facingPages == true) stories[i].paragraphs[0].parentTextFrames[0].geometricBounds = ([9.2,225, 18.6, 340]);

        if (stories[i].appliedParagraphStyle == STYLE && stories[i].paragraphs[0].parentTextFrames[0].parentPage.name == 3 && app.activeDocument.documentPreferences.facingPages == false) stories[i].paragraphs[0].parentTextFrames[0].geometricBounds = ([9.2,15, 18.6, 130]);

        if (stories[i].appliedParagraphStyle == STYLE && stories[i].paragraphs[0].parentTextFrames[0].parentPage.name == 4) stories[i].paragraphs[0].parentTextFrames[0].move([15,9.2]);

    }

}