Errors in the OLAP Storage Engine for a large dimension

A colleague of mine was working on a cube. The cube had a fact table that was also a dimension. It had 18 million rows of data. When my colleague tried to process the cube with that fact and dimension, he couldn't. Both the full and the incremental process didn't work. He got an error on processing the large dimension with a message of:

Exception calling "Process" with "1? argument(s): "File system error: A FileStore error from WriteFile occurred. Physical file: . Logical file: . . Errors in the OLAP storage engine: An error occurred while the 'RN' attribute of the 'YYYYY' dimension from the 'XXXXX' database was being processed.