Thanland sandstorms

Ever since I got this game, the sandstorms in the regions surrounding Ul'dah have always looked horrible. I just assumed it was my graphics card (and it still may be) and went on with my business. Today, I finally got fed up with it, and tried to mess around with options to make it stop. Thankfully, I fixed it rather quickly, but the fix makes me wonder if the problem isn't in my graphics card, and rather, in the system itself.

When "Extended Drawing" is off, the sandstorm flickers in and out like a strobe light. When it is on, it looks just fine.

Platform: Windows 7 64bit
ISP: AT&T (U-verse)
Type of Internet Connection: FiOS
Internet Connection Speed: 15/5mps
Date & Time: 10/8/2011
Frequency: Anytime there's a sandstorm occurring
Character Name: Raldo Volca
Race: Hyuran
World: Selbina
Class/Skill Rank: Shouldn't matter (THM 44 at the moment)
Area and Coordinates: Anywhere in Thanland that gets sandstorms
Party or Solo: Solo
NPC Name: N/A
Monster Name: N/A
In-Game Time: Daytime (didn't notice exact time, but it wasn't dark)
Steps:
1. Walk around Thanland during a sandstorm.
• With extended drawing ON, everything looks good.
• With extended drawing OFF, sandstorms look like a strobe light migraine waiting to happen.

Extra notes:
• I was on a chocobo today when I did it. I didn't test while I was walking, but unless something was changed in 1.19, it should happen when walking too.
• My graphics card is a NVIDIA GeForce 250M.