Does anyone know a solution to this issue with Gmail?

I have a PC laptop, and am using Internet Explorer 9 (Please do not castigate me for this choice. It is the browser I like). For about a week now, I have been experiencing an odd problem with gmail.

When I click on “Sent mail” or “Drafts”, instead of opening either of these selections, I am taken to whatever happens to be open in the last browser window that I used. This doesn’t happen all the time, but maybe about half the time. When it does, I have to return to the gmail window, and try hitting “Drafts” again… sometimes more than once. Annoying.

So, for example, if I have open gmail, Fluther, and Facebook, when I click “Drafts”, instead of seeing my drafts, I see Fluther.

It has definitely never sent me to anything other than a browser window. I just tried it now being logged into gmail on Firefox, and it didn’t happen (which doesn’t tell me much, since it’s not a consistent glitch), but this time when I tried to click “Drafts” in the IE gmail window, I was kicked to the Firefox window. That… seems weird to me.

Does anyone know why this is happening, and how I can correct it? Do you think it’s more likely to be a gmail issue or a browser issue?