Windows OS update som heter MS14-045 innehåller dock en bugg som lett till att ett stort antal användare av Windows 7 had their computers locked.
Of the comments posted on Microsofts supportforum it seems that the problem primarily affects the running 64-bit version of Windows 7. For many, the problem has been found in the form of a blue screen, popularly known as the "blue screen of death".
Some of the users have been able to solve the problem by restoring their installations to an earlier version before the update. However, it requires the user to have access to an installation source for Windows 7.
In an updated support documents for MS14-045 Microsoft now says that the company is researching this problem while asking users to uninstall the update and wait for an updated version.
Microsoft has also published a supportdokument describing how affected users can deal with the problem.