Users of CA eTrust Anti-Virus were forced to roll back an update posted last week after it caused the program to object to large numbers of innocent files, including some of its own.
The rogue update, identified as 33.3.7051, has now been replaced by version 126.96.36.19974, which reinstates an older version of the core malware-detection engine. In a post to its support forum, the company has also posted a tool that removes the false positive files on any system affected by the issue.
The number of users affected by the issue is believed to have been small, but would have rendered key elements of Windows and other programs inoperable, as well as de-activated itself.
"CA is aggressively working to resolve the issue, assist any customers who have been affected, as well as identify the root cause of the incident," said the company's last communication on the subject, on the evening of 12 August.
"We apologise for this inconvenience and look forward to the roll out of our new antimalware engine, which will ultimately offer our customers many benefits including enhanced malware protection and improved performance."
CA has asked affected users to visit the following website for more information, but has yet to re-schedule the original update for the software, which it also refers to under its old name, Internet Threat Manager (ITM).