Illustrator window often is hidden behind other windows, even if it should be on top.

I often have multiple windows open in Windows 10...like a web browser and email and perhaps some File Explorer wndows as well as a window for Illustrator CS5. Well, at times, I would be using it, naturally is the window on top...but sometimes, It falls under the other windows...and even click the tab on the task bar, doesnt bring it to the front. I literally have to minimize each window til I can see the Illustrator window, and when clicking on the window itself, not the tab, will bring it to the front again. I even had it fall behind the other windows with no warning. Is there a reason it does this? It is quite annoying when I'm looking resources or something to to help with a image an working on, or even just checking emails or someone messages me, and trying to bring it back to the front via clicking on the tab, for it to not work

Hope that explains it...I had this problem a long time, just wasnt sure how to articulate it properly...even when trying to google it, get results way off from what am looking for...and feel am just not wording the inquiry correctly.

Thanks