All orders being cancelled

I have been a long time Dell customer and I order Dell products for my customers. Every once in a while over the years, all my orders get canceled within seconds of placing the order. But then everything goes thru a few months later. Today I attempted several times and they all were canceled. Is my account on a blacklist? The orders I attempted were all Ship To and Bill To addresses I have used for years. I know the Bill To info is correct. Can you look into my account?