McAfee is offering technical and financial assistance after releasing a faulty update file last week that crashed thousands of Windows XP SP3 systems.
The company released the update on Wednesday, and quickly scrambled to make good after complaints poured in.
"I want to apologise on behalf of McAfee, and say that we're extremely sorry for any impact the faulty signature update file may have caused you and your organisations," said Barry McPherson, McAfee's executive vice president of support and customer service, in a blog post on Friday.
McPherson added that it was McAfee's belief that only a small number of PCs had been affected.
The firm updated its position on the problem late last night, and offered a worldwide recovery service for inoperable of severely impaired PCs, again suggesting that these would be in the minority.
"If you are one of a small percentage of McAfee consumer customers who has an inoperable or severely impaired PC as a result of the faulty file released earlier this week, we want to sincerely apologise for the inconvenience," the firm said in a blog post. "Our immediate priority is to get you back up and running."
Affected users can contact the firm's qualified technicians through a local free phone number, except in the UK where other charges may apply. The technicians are "standing by" to diagnose and fix problems.
If this is not successful, McAfee will offer a fix via download, or will express deliver a CD to the user's home or office.
The company is also offering "reasonable expenses" to any home or home-office users who have incurred costs as a result of the update. For example, it will reimburse users who had to visit a local tech support specialist. Details of how to claim, and what to claim for, will be released in the next few days.
McAfee is also offering a free two-year extension on users' current subscription.
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