OK, after reading Brunen's post and reviewing mcfrojd's post, I think we may be experiencing different things.
First, there is a memory leak (probably more than one), that began in version 3.1. I've been trying to track down exactly what's causing it so I can fix it. It won't affect most people because it seems to happen mostly when the screen changes. I can cause the TD to crash or freeze by creating a Screen Set that switches screens once every second. After a few minutes the memory size gets big enough to cause problems (about 1.6GB seems to be the magic number, if I recall correctly). If your layout doesn't switch screens, or switches screens every 30 seconds or couple of minutes, you'll probably never care about this.
Second, there is a ... condition, I guess, because it doesn't seem to be an issue for me, in which IE renders dialogs black. But for me it only happens when the dialog first opens, and only for a brief moment. I don't think I've ever seen a dialog stay black for more than 2 or 3 seconds. Most of the time the dialog either never renders black, or renders black for such a brief instant that you can't see it without really looking closely for it. Even now, I'm trying to use a screen recorder to capture what I'm seeing, but I can't even get it to happen for more than a single frame, so it's basically invisible. This is an Internet Explorer thing, and there's nothing the TD can do (that I am aware of) to alleviate it. But it's little more than an annoyance. And as such, unfortunately it's unlikely Microsoft will exert any effort to fix it. Here's to hoping they fix it as a by-product of fixing something else.
It sounds to me like you might be seeing a different issue, where dialogs that are already open turn black? Or they open black and never render properly at all?