It's not uncommon to have problems with The Sims 2 on Windows 7, 8, 8.5, and 10. I've had all of these versions of windows and had trouble running The Sims 2 on all of them. The Sims 2 is my favorite Sims game so naturally I searched the internet for fixes and Troubleshoot Forums. Here's what I found:
Black Flickering This is caused by your graphics card not agreeing with the game. Turn Shadows to Medium or turn them off completely.
That's the simplest fix. If you're also having any of these: Screen flickering, Black screen, graphical errors, pie menus won't load, gameplay errors, shadows still flickering, mods won't show up.
First, before doing any more fixes, remove your mods folder and all mods if you have any, just to be safe.
Second, download Graphics Rule Maker from SimsNetwork:
This program, (Virus free, I checked) is made to fix all the problems listed above except for the mod issue. Let it find your Sims 2 game, add your graphics card to its database, set your screen resolution, and apply the fixes. (But try to avoid using all the fixes if possible)
I personally used this and it fixed my Sims 2 game 110%. Looks better than it did before.
Now for the mods, check the in game options, there's a section to toggle the mods on and off. Check on and that should fix it, if it doesn't then its a deeper problem.
So there ya go! Enjoy The Sims 2!