The hole that Dell Inc. has been trying to dig itself out of got a little deeper yesterday.

The personal computer maker said an internal investigation found accounting errors, "evidence of misconduct and deficiencies in the financial control environment." Dell said it would not file its annual financial report with the Securities and Exchange Commission until its investigation was complete.

"The Audit Committee is working with management and the company's independent auditors to determine whether the accounting errors necessitate any restatements of prior period financial statements," the company said in a statement.

It was issued after the stock market closed. Shares ended at $23.39, up 4 cents, and fell to $22.83 in after-hours trading.

The company's troubles began last year. In August, the U.S. Attorney's Office and the SEC said they were investigating Dell's accounting practices. The company's board then launched its own probe.

Dell has revealed little about it except to say it doesn't involve the issuing of stock options to employees or how it accounts for revenue. Last September, the company said its investigation was focusing on "the possibility of misstatements" and "issues relating to accruals, reserves and other balance sheet items."

Based in Round Rock, Texas, Dell transformed the PC industry by selling directly to consumers and businesses. Competitors that sell in retail stores or through third parties have been stealing customers in recent years. Dell has been particularly hurt by slow growth in the PC market in industrialized countries, where it has dominated, and for not capitalizing on the demand for notebook computers.

Hewlett-Packard Co. at the end of 2006 surpassed Dell as the No. 1 seller of personal computers globally. There was another blow last year when Dell had to recall Sony batteries in some 4.2 million laptops that were overheating.

In January, Chairman Michael Dell reclaimed the title of chief executive, jettisoning Kevin Rollins, whom Dell had handpicked.

In February, the company was hit with a class-action suit from shareholders who claim Dell inflated its profits by recording as revenue undisclosed rebates from chip maker Intel Corp.

A few weeks ago, Dell reported its fourth-quarter results and said that quarterly sales had declined for the first time in five years.

"We'll look back at this as a bad period for Dell," said Martin Reynolds, a vice president at Gartner Inc., a research firm based in Stamford, Conn. Yesterday's announcement about misconduct, Garnter said, isn't "any more damaging than anything else going on."

Reynolds said he believed Dell would ultimately be able to dig itself out. "They are a company with a lot of resources. They just have to pick the right businesses to pursue and the right channels."