I post this because when I try to access to the advanced sky from the Environment Editor (CTRL+ALT+E/CTRL+META+E), I get extremely low performance rates, meaning I am not able to edit the sky. The interesting thing is, it just happens when I access this menu, even if I don't change ANYTHING.
Also, it is funny that I have a great performance rate (even better than the official SL viewer) with things on medium/high graphics, but they just go low if I access the sky editing menu (Advanced Water also has a little performance issue, but it is almost not noticeable).
I've tried disabling shaders and rendering types while I am in low performance, and lowering the details... but it results in nothing, making me restart SL... and there we go... everything set to high and it goes neat again, but if I access that menu, I have to restart the viewer! (It keeps going slow even if I close the menu)
Does anybody have this problem or a fix to it?

Thank you!
P.S: This happened too in the previous WindLight viewer.
P.S: My graphics card is a nVIDIA GeForce 7600 GT, under a 32 bit 2.6+ single core AMD with an Abit AN-7 as motherboard, and Windows XP (Service Pack 1) as operative system, if this information helps.
[UPDATE] Seems like the Linux versions runs perfectly, but for some reason it does not like Windows. I still don't know why does this happen. (I guess if it was a virus, spyware or any application doing that, it should start going slow since I run it for first time)
[UPDATE 2] Bleh... I give up... nothing I do works. If somebody had this problem and found a fix for it, I will greatly appreciate the help!
[UPDATE 3] Argh! Yes! It was Windows... I migrated to Service Pack 2 and now it works fine... O.o...