A group of former shareholders in Rock Band developers Harmonix - including company CEO Alex Rigopulos and his co-founder Eran Egozy - are suing parent company Viacom, amid claims massive bonus payments are being avoided.
According to a report on Gamasutra, it appears that as part of the deal which saw Viacom purchase Harmonix back in 2006, there were several notes in the contract relating to "earn out" payments. These were essentially bonuses, which if Rock Band passed certain sales thresholds would be paid to Harmonix shareholders.
In 2007, most of these payments were made, and totalled around $150 million. But in 2008, with sales of Rock Band going through the roof, it's alleged Viacom sought to dodge a bullet (mostly by renegotiating distribution deals with Electronic Arts) and find ways to avoid paying what would be further, enormous sums of money.
This is in addition to Viacom's attempts at recovering the money it's already paid.