From the Chicago Tribune:
The Social Security Administration's mainframe computers based in Maryland were back up this afternoon [Thursday] after being offline for several hours, a Chicago-based spokesman said.
The mainframe system situated on the East Coast that serves the entire country went down this morning, affecting the processing of claims for beginning retirement and disability benefits, among other services, said Doug Nguyen, a spokesman for the government agency in the Midwest. It was functioning again by early this afternoon, but systems analysts wanted to make certain the computers were working before announcing it, Nguyen said about 4 p.m.