A tax benefit helped to boost fourth-quarter revenue at Western Digital ( WDC), but the improved results were offset by news that the company has found discrepancies in its historical stock-option grants.The data storage maker said late Thursday that a special committee of its board has made a preliminary determination that measurement dates for accounting purposes may differ from recorded dates on grants made from fiscal 1999 through 2003. The company said it doesn't anticipate a material adjustment to the operating results reported Thursday. However, depending on the results of the review, "a material adjustment to the company's financial statements could be required." Shares of Western Digital were halted before the announcement. In those operating results, the company said net income for the quarter ended June 30 rose to $119.9 million, or 53 cents a share, from $41.2 million, or 19 cents a share, a year earlier. Net income included in the latest quarter included about $35 million in favorable adjustments, $22 million of which was due to a favorable tax benefit. Revenue rose to $1.09 billion from $940.4 million a year earlier, essentially in line with the Thomson First Call estimate of $1.08 billion. First Call was expecting EPS of 35 cents a share, but it's unclear if this figure reflects the reported adjustments in the quarter's results.