Dell Inc. executives have finally wrapped up a yearlong internal investigation into accounting problems at the computer company, and the mistakes could end up costing them as much as $150 million.

”This is not a happy story for Dell nor one that we’re terribly proud of,” Vice Chairman and Chief Financial Officer Don Carty said Thursday after Dell announced it would reduce more than four years’ worth of earnings because it misled auditors and manipulated results to meet performance goals.

The beleaguered company said its net income for the restatement period – all of fiscal 2003 through 2006 and the first quarter of fiscal 2007 – will be reduced by between $50 million and $150 million, or 2 cents to 7 cents per share.

The largest reductions in quarterly profits were expected to be in the first quarter of fiscal 2003 and the second quarter of fiscal 2004, each lowered between 10 percent and 13 percent.

The investigation, which began in August 2006 and evaluated more than 5 million documents, ”identified evidence that certain adjustments appear to have been motivated by the objective of attaining financial targets,” Dell said.

Round Rock-based Dell said unspecified terminations, reassignments, reprimands, increased supervision, training and financial penalties either have been or will be taken as a result.

Analysts who questioned Carty during a conference call repeatedly asked if any current executives were privy to the accounting woes.

Without naming names, ”the ones that knew about it are the ones that are gone,” said Carty, the former chairman of American Airlines. ”Let me assure you that both the leadership team of the company and the board feels that we have absolutely taken the necessary action.”

The Securities and Exchange Commission’s investigation into some of Dell’s accounting and financial reporting practices is ongoing, the company said. Dell still faces shareholder lawsuits, and federal prosecutors in New York subpoenaed documents on the company’s financial reporting since 2002.

One analyst, however, said the financial impact would be minimal given Dell’s multibillion-dollar size.

”The magnitude of this stuff is very small, it’s not a big number,” said Roger Kay, president of Endpoint Technologies Associates Inc. ”I don’t think it’s anything that’s going to rise to the level of criminality, but then again I’m not the SEC.”

Dell shares rose 3 cents to $25.96 in morning trading Friday.

It’s been a tumultuous time for Dell since the probe was first revealed last August.

Dell’s executive team has undergone significant changes, including the departure of former Chief Financial Officer James M. Schneider and the return of Michael Dell as its chief executive officer.

Since then, Dell has seen its domination of the PC industry slip to rival Hewlett-Packard Co.

Dell lost its No. 1 grip on the PC market last fall while HP continues to gain footing. But in the second quarter, HP had about 19 percent of the worldwide PC market compared with Dell’s 16 percent, according to market research firm IDC, citing the most recent data available.

Dell said the findings announced Thursday would not have a material impact on second-quarter results, which are scheduled for release Aug. 30.

The company has issued only preliminary financial results for the four most recent quarters and hasn’t filed its annual report for the fiscal year that ended Feb. 2 because of the ongoing investigations.

With the internal probe complete, Dell said it expects to file the past-due documents by the first week of November. Its annual shareholders meeting is scheduled for Dec. 4.

”We’re not terribly proud that we found one element of our company that wasn’t world class,” said Carty. ”None of us at Dell like this.”