FIrm promises to stop it happening again.
PCs powered by Microsoft's Windows XP operating system were not able to access the Internet or company networks after installing a faulty anti-virus update from Kaspersky Lab.
The Russian IT security firm advised users to disable its anti-virus software or roll back the update.
A Kaspersky representative said in a statement that the issue was caused by a database update released on 4/2/2013 at 8:52:00PM Moscow Standard Time [MSK] that resulted in the Web Anti-Virus component in some products blocking Internet access.
"The problem only affected x86 systems with the following products installed: Kaspersky Anti-Virus for Windows Workstations 6.04 MP4; Kaspersky Endpoint Security 8 for Windows; Kaspersky Endpoint Security 10 for Windows; Kaspersky Internet Security 2012 and 2013; and Kaspersky Pure 2.0," the representative said.
Later the firm issued a fix through a database update, while users were not able to auto-install the new code from the net and had to execute several tasks initially.
"Kaspersky Lab would like to apologize for any inconvenience caused by this database update error. Actions have been taken to prevent such incidents from occurring in the future," the representative said.