it happened to me the other day, its not due to the Golf GTi site
good news is that you can fix it easily
clear history, cookies and data from your settings (not just within browser), make sure the pop window/m0birewards site isn't open when you clear your data
then reset by holding the home button and power button until the apple logo appears
its very annoying when it happens and no one is sure why... it might be due to a rogue app but no one is really sure