Bloom's alphas disappearing... ??

Edit: Well... I've answered my own problem. Four years playing the Sims 2 and I've only just discovered the graphics options on alt start up. Unchecking the Optimise Rendering box allows me to set the correct screen res for my new LCD and keep ALL custom content visible (no more transparent dresses or blacked out skintones), and makes the game run a lot more smoothly into the bargain.

I have several re-colours of Bloom's multi-mesh outfits that I've downloaded (mainly 34C, Fashion Model and Pin Up sizes), and from which I have fashioned some re-colours of my own. All was well with these until today when I changed to a new LCD monitor.

Now, the original downloads still appear as they should, but all of my own re-colours have turned transparent... or rather the alpha parts have.
I have a feeling this is probably due to something really obvious but have no idea where to begin in solving the problem, so any help would be welcome. I don't know whether this is a resolution issue, a skinning issue or a combination of the two.

If this helps, my screen res is 1440x900 at 60 Hz, but I can only successfully set the game res at 1280x800 (I expected this because my previous monitor was 1280x1024 and I could only ever get the game to run properly at 1024x768).

I'm stumped!

Nina XX