The problem started Nov. 9 when AVG released a virus signature update that misidentified the user32.dll file, a core Windows XP file, as a Trojan, causing the company's antivirus software to ask the user whether to delete the file. Those who answered yes found that their machines either wouldn't boot or would go into an endless reboot cycle. AVG released a fix within hours after the snafu was discovered, but not soon enough to prevent damage to some customers' computers.
As a result, the company said it would offer affected users of AVG 7.5 a one-year license for the equivalent 8.0 upgrade at no charge. Users of AVG 8.0 can get a free one-year license extension, and people using AVG's popular free antivirus software can get a one-year license to the commercial version at no charge.
The company plans to start contacting affected customers Nov. 24 to tell them how they can obtain their freebies.
"AVG Technologies apologizes again for the inconvenience caused to our customers and wishes to assure our users worldwide that the company is actively putting new processes in place to avoid similar occurrences in the future," the company said in a statement issued late Thursday.
The incident was not the first time AVG, based in the Czech Republic, has released virus signatures with a false positive. The company's software less than a month ago misidentified Check Point's ZoneAlarm as a Trojan, according to the U.K. tech site the Register.