imagegrabwindow + https = black screen

I'm doing something stupid and trying to capture thumbnails, snapshots, images of a html webpages.

I'm doing something along the lines of:

How might I obtain a Snapshot or Thumbnail of a web page using PHP?

DCOM + IE + PHP (imagegrabwindow; example from manual)

Everything works PERFECT until I try to capture a HTTPS website... https://mail.google.com for example.

imagegrabwindow produces a png, but it only shows the browser. the contents of the browser are black. If I log out of Google, I can capture the browser window and the contents thereof - the second I log in, the contents (not the browser frame) are black screen.

Yes, I've increased the timeout (before closing the browser window). IE has clearly loaded the page, it just refuses to render for imagegrabwindow.

I've been fighting this long enough I know it's either a permissions problem or a service needs to interact with the 开发者_运维知识库desktop.

Does anyone have any clue what permissions need to be set or which service needs access?

I assumed cryptographic services, but that's run as a network service and trying to change it to interact makes it shout and carry on.

This is the last piece of the puzzle, I'd really like to get it working. Thank you!