Less than a month into its latest book-cleaning effort, Nortel (NT) has already suffered another setback.

The Toronto telecom-equipment maker says it has discovered more misbooked revenue, beyond the

nine-figure tab it toted up March 10. "Additional revenue recognized in prior periods will be restated and deferred to future periods," the company said in a press release late Thursday.

Nortel could not say how much money would be added to the restatement. The latest round of blunders comes after investors endured a lengthy bonusgate scandal that led to a nearly complete turnover in the company's highest management ranks.

With new hard-charging chief Mike Zafirovski at the helm, Nortel watchers have been expecting to see signs of progress. But fans were shocked to learn last month that the company still hasn't fixed its past accounting troubles.

On March 10, Nortel said it expected a restatement to lop $162 million out of revenue and $95 million from net income in the first nine months of 2005.

Those restatements will reduce 2003 and 2004 revenue by about $234 million and earnings by $184 million, Nortel said. Previously filed financial statements aren't reliable, the company said, and a material weakness continues to exist with regard to its financial controls.

Some observers say Nortel's new accounting slipup may have

cost it a chance to combine forces with

Alcatel

(ALA)

. Alcatel and

Lucent

(LU)

announced a $13.4 billion merger earlier this week.

Nortel shares were unchanged at $3.06 in early trading Friday.