I have a strange graphical anomaly going on my iMac right now (green and magenta boxes are appearing sporadically), I'm slowly trying to work through different possibilities but I thought I'd start with the basics:

Can a graphical anomaly that I can screen capture still be a hardware issue?

I know, it seems really obvious. If it's hardware, it should show up well after the operating system has had it's say. And since the operating system is (I assume) doing the screen capture, it seems like it shouldn't see the anomaly unless the problem is software in nature.

But, as I've researched this problem I see a lot of people taking their computers in to service people for hardware issues and Apple then resolving said issue.

To further complicate things, I also have Windows 8 installed via bootcamp, and the issues seems to be showing up there as well.

Anyway, it feels like it must be a driver issue, since I assume that's what the two OSes have in common, but...I thought I'd come here for some disambiguation.

In my case, yes, I can screen capture the anomaly (at least in OSX I can), so I assume it's somehow a software (or driver) issue. But I wanted to double check because the internet is being ambiguous...