I was having the same issue, every now and then I would get a popup stating that my Credit Card had expired.

Here is what I did to clear up the issue:
1. From the Company menu, select Reminders.
2. Under Business Service Messages, double click on credit card has expired.
3. Hit the button I’ve already done this. after viewing the reminders.
4. Open the Reminders option again from the Company menu. From there, the Business Service Messages should not show the warming that your credit card has expired, and the popup should no longer show up.

If doing this does not make a difference, I recommend giving support a call.