I have an annoying problem that is either rare or I just can't find the right keywords to describe it to Google.
I use W7, and always have several Visual Studio (2013) instances opened at once. I often need to switch from one to another, but Alt+Tab only shows one VS instance. Actually it sometimes shows me several instances, but they seem to "merge" when I switch from one to the other with ALT+TAB. This does not happen for other applications, and I don't remember having this problem in the past.
I turned Aero off, but the classic theme works exactly the same.
Edit: for some reason the problem is not happening anymore right now and I'm not sure why. I did put both currently running instances side by side on the screen (Win+Right, Win+Left), and now that both windows are maximized again, the merging doesn't occur anymore... Correlation or cause?