Shopping cart to checkout problem

Getting a message.... Sorry, we can't complete your checkout at this time. Please try changing your item quantity or check your account status,,,, Have logged in a few times, everything seems OK and have paid for other items from other sellers, the one difference on this issue is I have asked that multple items be sent together to save postage and packing which was granted. If I knew the **bleep** this would start I would have just paid the extra. Any idea's would be appreciated