this happens a lot with the 08's... we finnaly got it fixed so that they dont do that... you can do 2 diff things... add a relay harness to them or get better ballasts....
with HID's you get what you pay for.... sometimes those cheap ebay HID's work for a while and sometimes they dont...
contact who you bought them from and tell them whats going on and see if they wont send you a relay harness for free... if not its prob gonna cost you around 30-40 bucks for a relay harness....
if you have any questions please let me know
-Raul