WASHINGTON/NEW YORK, Oct 28: A data center critical for allowing uninsured Americans to buy health coverage under President Barack Obama’s healthcare law went down yesterday, halting online enrollment for all 50 states in the latest problem to hit the program’s troubled rollout. The data center operated by Verizon’s Terremark experienced a connectivity issue that caused it to shut down, affecting the federal government’s already problem-plagued online marketplace Healthcare.Gov and similar sites operated by 14 states and the District of Columbia, according to the U.S. Department of Health and Human Services (HHS). (agencies)