Microsoft is re-releasing the patch that caused Windows systems to crash in February with a Blue Screen of Death.

The software maker has re-written the installation package for the update, MS10-015, and will push it out automatically to users. It has written logic into the update to prevent the fix from being installed if the Alureon rootkit is present, it said in a Microsoft Security Response Center statement.

The Alureon rootkit, which makes changes to the operating system kernel, caused the February crashes, according to Microsoft. “I am writing to let you know that we have revised the installation packages for MS10-015 with new logic that prevents the security update from being installed on systems if certain abnormal conditions exist,” wrote Microsoft’s senior security communications manager lead, Jerry Bryant, in the statement. “Such conditions could be the result of an infection with a computer virus such as the Alureon rootkit. If these conditions are detected the update will not be installed and the result will be a standard Windows Update error.”

Windows users, primarily those on XP, were hit by the Blue Screen of Death (a succession of system error messages) after Microsoft first released the update on 9 February. Microsoft soon suspected the crashes were due to malware, but delayed re-releasing the patch until it identified the cause.