NEW YORK (CNN/Money) - Cable-TV operator Adelphia Communications said Friday it is being investigated by federal prosecutors just a day after the company's CFO quit and two days after the CEO, also his father, stepped down.

While the Coudersport, Pa.-based company said grand juries from the Southern District of New York and the Middle District of Pennsylvania are investigating certain matters related to the company, executives did not specify what prosecutors are seeking to find.

Adelphia said it is cooperating with the grand jury investigations.

Separately, the sixth-largest cable company in the United States said it missed $38.3 million in interest payments due on Wednesday and some dividend payments and is evaluating financial requirements and business objectives.

"The company decided not to make these payments on outstanding bonds and preferred shares because we are now pursuing a thorough evaluation of Adelphia's business objectives and financial requirements," the company said in a statement. "Adelphia has valuable assets, and we are working to restore the confidence of our lenders and shareholders."

The company said it plans to pursue a previous objective to sell assets in order to cut some debt.

Adelphia also said it had a hearing Thursday with the National Association of Securities Dealers (NASD) about the possible delisting of its shares from the Nasdaq stock market, but no immediate decision was made. Nasdaq suspended trading in Adelphia's shares on May 14.

On Thursday, Adelphia Chief Financial Officer Timothy Rigas left the company a day after his father, John Rigas, stepped down as CEO. Both men said they would retain their seats on the company's board.

The SEC is probing Adelphia's accounting for $2.3 billion in off-the-books debt. Adelphia disclosed the investigation April 3. The debt includes loans, possibly as much as $500 million, made to members of the Rigas family, who apparently secured the loans with Adelphia's assets.

Earlier this month Adelphia said it expected to restate its financial results for three years to reflect the off-the-books debt, worth about $1.6 billion on May 2, and that it was reviewing its accounting methods.

Shares of Adelphia have been halted since pre-market trading on Wednesday