Since yesterday, Kaspersky anti-virus software is apparently causing serious problems in some corporate environments. There have been complaints in forums (German language link) from administrators of servers running with Kaspersky Anti-Virus about high system load - high enough in some cases to stop the whole system. The reports concern Windows server with Kaspersky Anti-Virus 6.0 for Windows Servers Enterprise Edition, whether other versions are affected is unclear.
Kaspersky has since confirmed that on Saturday evening, a faulty update for Kaspersky Anti-Virus 6.0 for Windows Servers Enterprise Edition was published. This led to the described load problems on Windows server systems.
As a temporary work around, administrators of affected systems were advised to disable the signature auto-updates and to roll back to an older signature status. Today, October 25th at 12:46, Kaspersky released a further update to correct the problem.
Also : Misfiring Kaspersky update reduces servers to a crawl