Let me guess; these were checks written to you and you cashed them.
I suspect the checks were for cash advances which if cashed, means you opened a credit account with the issuer and since you haven't made payments as the accompanying agreement stated, they have reported negative activity on your credit report.
While that's a lot of guessing, I can't think of much else that would start with;
Bank sent me checks
And ended with;
Now they're on my credit report.