diff --git a/Known-issues.md b/Known-issues.md
index dcb0193..65f6bb6 100644
--- a/Known-issues.md
+++ b/Known-issues.md
@@ -72,6 +72,7 @@
    * 9on12 can also cause games to hang or crash - e.g., SDVX VW, IIDX32+, etc
  * Third party DirectX-reimplementations (e.g., dxvk, ForceD3D9On12) may occasionally cause crashes in the weirdest ways; if you encounter random crashes, please try running the game without them. No support will be provided for these.
  * Having NVIDIA RTX Voice (or other NVIDIA applications) open sometimes causes games to randomly crash in fullscreen.
+ * Some older games do not like it when you alt-tab out of the game or loses focus while in full screen. This is unfortunately a limitation of XP-era DirectX9. Newer games that use DirectX9Ex APIs do not have this problem.
 
 # Game-specific