CANNOT PRINT LABELS SINCE 03/12/13 a.m.

CANNOT PRINT LABELS SINCE 03/12/13 a.m. When clicking the "Next: Billing Information", receive the following error since yesterday morning :

• We are sorry but we were unable to process your order. Please re-edit your labels and try again.

Have tried logging in with different browsers and deleting all labels then re-entering...still no help. The "Online Chat" assistance does not work and I have been on hold with USPS website tech support over an hour.