Exchange mail users cannot send to certain lists
Solution 1:
Found out that it was what everyone was suggesting. When I made the Staff distribution list from a standard list to a dynamic list, something got messed up. I went into OWA, brought up the nickname cache (little pop-up menu when typing in the address in a new mail) and hit delete on the name, it removed it from the nickname cache. When they tried to send again, it sent to the correct list.
Thanks for everyone's help!