Freezing/Crashing when switching active window

Time: Currently 6:34PM CST, but it last happened around 2pm.
Frequency: Intermittent/Random. Over the past week or so.
World name: Siren
Character name: Shanra Laenahyi
Class/Level: Any and all
Party or solo: Both
Area and coordinates: Anywhere (In Foundation/Pillars, in Gridania, in various towns, out of town in the world, etc)
Steps:
1. Open game (using DX11 & running borderless windowed)
2. Open any other program at all (Tab out/Windows Start Menu/Click on second monitor's screen)
3. Rinse repeat until game freezes. (all visuals freeze, and clicking on the game causes the the "Processing" circle to appear, clicking again gives me windows asking if I want to close/wait/report)
Seems to be about 20% of the time... If I stay out, I can switch between all other windows multiple times with no issues, it's just swapping from FFXIV to another that triggers it. Occasionally, if I close the program I was using when I swapped out initially it'll unfreeze, but that's not a guarantee. It's frozen when Chrome is swapped, it's frozen when I opened a Calculator to figure out how much the next step in crafting will give me... it's frozen when I've alt-tabbed to check a recipe for someone on a craft I don't have. Other times I can tab out 10+ times with no issues.


PC Specs
-=-=-=-=- System Information -=-=-=-=-
AMD FX-8350 Eight-Core Processor 4.00GHz
32GB RAM
64bit OS
Windows 7 Professional SP1
AMD Radeon HD 6570

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Browser Information
- Name and version of the browser currently in-use: Google Chrome 57.0.2987.133 (64-bit)


I did see some people having what sounded like similar issues on other forums (though searching here I couldn't find the exact issue) and they talk about "overlay" programs... The only other software I'm running is MSI Afterburner to maintain the speed of my fans (GPU is prone to overheating with default speeds) and Razer Synapse so when I plug in my headset to use Teamspeak the game sounds don't vanish. I don't run this game through steam anymore since it decided to delete my game a week ago, although ironically, that's around the time I started having this issue.