It appears that Xbox Live is going all sorts of wonky due to some technical issues related to billing.
Lieutenant Larry Major Nelson spilled the beans on the problems:
Just to see if the good Major was fibbing, I went to Xbox.com to see if I could log in (yes, I'm one of those people that touches their plate after the waitress warns that it's hot). The "sign in" button has been removed, as of this writing. I logged onto my account through Xbox 360 and purchased some dolly clothes for my Street Fighter IV characters. That worked out fine. The issue appears related to adding points or extending gold membership.
Anyone experiencing any of the issues Larry the marketing guy wrote about? Please let me know!