Does your issue have anything to do with Excel, or it is affecting the windows of other programs?

OK, it looks like Alt+Tab is working as it used to with Excel but only if you've opened up a separate instance of Excel. If you're working in one Excel file and open a second from within that...

I may not have explained it very well. It used to remember the previous window I was on and flip back and forth between that window and the one I'm currently viewing. Having multiple Excel files open...

After some further investigation, it seems that at least in my case the issue is specific to Excel. If I have two Excel spreadsheets open and a third window of another program, and I'm currently...

I have the same problem as the OP, and the solution proposed by Voyager doesn't work for me.

What I would like to be able to do, and I think the OP would as well, is to be able to flip back and...