Microsoft has already taken a $900 million hit on the Surface RT but it soon may have to pay out even more. AllThingsD reports that law firm Robbins, Geller, Rudman, & Dowd has filed a complaint against Microsoft alleging that the company misrepresented sales of its Surface RT tablet to investors. In particular, the firm says that Microsoft should have warned investors much earlier that it had a stockpile of millions of Surface tablets that it was unlikely to sell.

“What Defendants knew, but failed to disclose to investors, however, was that Microsoft’s foray into the tablet market was an unmitigated disaster, which left it with a large accumulation of excess, over-valued Surface RT inventory,” the complaint alleges. “Defendants’ materially false and misleading conduct enabled Microsoft to forestall Surface RT’s day of reckoning and delay what would be tantamount to an admission by the Company that its all-important entry into the tablet market had been a failure.”

Microsoft understandably declined to comment on the suit.