Ridiculous PO problem I'm having

I love GP3 but this is something that's annoying me greatly. PO is kinda normal (relatively, that is. 100% PO for a computer made in 2008 isn't right) when it's raining or if there's a few clouds in the sky. However, in clear blue sky, the game's PO rockets up to, I kid you not, 900%. This renders the game completely unplayable and not-at-all fun to play.

I've literally searched for a good couple of years to find a solution, but I have found nothing. Zilch. Zero. Nada. Nil. Nope.

If anyone can help, please do. I will love you forever if you can help me fix this. My OS is Windows 7 32bit with an ATI Radeon HD 4800 Series graphics card if that helps.

(and please do not tell me to set a custom weather setting. It's not a proper solution to the problem)

sorry, start here:
->link
(at the end a winXP-partition did it in this case)

but there where many, many other told solutions in the last year here in this forum. search!

Have you tried decreasing the fps rate in ""options -> graphics -> advanced""? Decreasing fps might decrease the fps ":D", but might help to make the game work fast (it usually helps for me).

Surely the problem is the video card .. I had bought a similar card (ATI Radeon) and I could not play. You may try changing the card, Nvidia is fine.

I really don't want to have to dual boot just for one game, but I may resort to it if I'm really, really desperate.

As for the video card, I may try it on another computer that I got recently. It uses a Nvidia card, but it's 64 bit Windows 7. I'll try it though.