A group of shareholders of MSC.Software Corp. is mounting an investigation into the board of directors’ agreement earlier this week to sell the company to Symphony Technology Group, a private equity firm.

Under the definitive agreement, Symphony will acquire all of MSC’s outstanding shares in an all-cash merger transaction valued at roughly $360 million. Stockholders in the simulation software company will receive $7.63 per share of common stock, which the companies said represents a 13% premium over the closing price at the time of the announcement.

Symphony’s enterprise software and services investment portfolio of nine companies includes Symphony Metreo, Aldata, IRI, and the publicly held Lawson (via its controlling interest in Intentia, which Lawson purchased in 2006).

“MSC has a long history of driving innovation in the design simulation space for multiple industries,” said Romesh Washwani, CEO and managing director of STG, in a statement. “Symphony’s mission is to be a partner in helping to build great companies and in enabling growth through innovation, so we are very pleased to have the opportunity to build upon the strong franchise that the MSC team has developed over the past 45 years.”

As executives touted the deal and the board recommended that stockholders give it their approval, the reaction was not altogether positive. The law offices of Howard G. Smith announced today that it is investigating “potential claims against the board of directors” of MSC related to the agreement with Symphony. The firm’s statement said, “The investigation concerns possible breaches of fiduciary duty and other violations of state law related to approval of the proposed merger by the MSC.Software board of directors.”

MSC’s largest stockholder is Elliott Management Corp., a private investment firm, which is a party to the agreement and is committing debt and equity financing to help fund the transaction. Wells Fargo Foothill and CapitalSource will also provide senior debt financing.

“This will allow MSC to continue to deliver innovative solutions in the simulation software sector,” said Jesse A. Cohn, portfolio manager at Elliott, in the statement. “As a significant equity holder in MSC, we will maintain our ownership alongside STG, which has a strong track record of building outstanding software companies.

Elliott is the umbrella company of Elliott Associates, which last year made a series of unsolicited offers to buy ERP provider Epicor Corp. The companies finally called a truce in February 2009, in which they agreed to a “standstill period” of one year, during which time Elliott could accrue more stock but would not make further bids to buy the company. Meanwhile, Epicor management remained in control, but agreed to expand the board from five to seven members as a concession to Elliott.

As Elliott had intended to do with Epicor, the MSC acquisition would create a privately held company.