Someone had to say it.
I've actually had trouble with AdWords wrongfully denying a credit card. So, you could either call G @ 1-866-2Google, or add a different credit card in the billing preferences.
You might also want to check with you credit card company. Sometimes they think they are protecting you by denying a purchase that appears to be drastically different from the other items purchased on your card (in case someone else is charging on your card).
ZagZag, if post 8 in the thread that eWhisper pointed to doesn't help you to pinpoint your issue, then my best advice would be to write to AdWords Support using the 'Contact Us' link within your account. Be sure to fill in all the fields in the header.
Or, as an alternative, use the toll-free phone number that has been posted here several times of late.
I hope you'll be up and running soon!
AWA
i just check all settings that recmmendet in [webmasterworld.com...] and it's seems ok, so i write message to google's support (using Contact Us link) with "ATTENTION ADWORDSADVISOR" in subject line, so i hope AdWordsAdvisor can control this.
I think they tried debiting when it was daytime at Google and night here - night, when systems are commonly taken down for periods.