Hi
I have the same problem on 4 Linux mail server with kav4mailservers-linux-5.5-33 antivirus, from 2:00 AM last night update doesn't work.
Here is message from log file:

[02/09/08 13:01:01 I] Start update for 'Kaspersky Anti-Virus for Mail Servers'
[02/09/08 13:03:36 I] Update source 'http://dnl-14.geo.kaspersky.com'
[02/09/08 13:03:36 A] File 'master.xml' downloaded
[02/09/08 13:03:36 A] version: 1220366280
[02/09/08 13:03:46 A] File 'kavset.xml' downloaded
[02/09/08 13:04:00 A] File 'kavset.xml' downloaded
[02/09/08 13:04:04 A] File 'base297c.avc' downloaded
[02/09/08 13:04:05 A] File 'dailyc.avc' downloaded
[02/09/08 13:04:05 A] File 'daily-ec.avc' downloaded
[02/09/08 13:04:06 A] File 'daily.avc' downloaded
[02/09/08 13:04:08 A] File 'fa.avc' downloaded
[02/09/08 13:04:08 A] File 'avp.set' downloaded
[02/09/08 13:04:08 E] Wrong file signature
[02/09/08 13:04:08 E] Failed to download files
[02/09/08 13:04:08 I] Update source 'http://dnl-08.geo.kaspersky.com'
[02/09/08 13:04:09 A] File 'master.xml' downloaded
[02/09/08 13:04:09 A] version: 1220366280
[02/09/08 13:04:13 A] File 'avp.set' downloaded
[02/09/08 13:04:13 E] Wrong file signature
[02/09/08 13:04:13 E] Failed to download files
[02/09/08 13:04:13 I] Update source 'http://dnl-06.geo.kaspersky.com'
[02/09/08 13:04:13 A] File 'master.xml' downloaded
[02/09/08 13:04:13 A] version: 1220366280
[02/09/08 13:04:18 A] File 'avp.set' downloaded
[02/09/08 13:04:18 E] Wrong file signature
[02/09/08 13:04:18 E] Failed to download files
[02/09/08 13:04:18 I] Update source 'http://dnl-01.geo.kaspersky.com'
[02/09/08 13:04:24 A] File 'master.xml' downloaded
[02/09/08 13:04:24 A] version: 1220366280
[02/09/08 13:04:30 A] File 'avp.set' downloaded
[02/09/08 13:04:30 E] Wrong file signature
[02/09/08 13:04:30 E] Failed to download files
[02/09/08 13:04:30 I] Update source 'http://dnl-04.geo.kaspersky.com'
[02/09/08 13:04:30 A] File 'master.xml' downloaded
[02/09/08 13:04:30 A] version: 1220366280
[02/09/08 13:04:34 A] File 'avp.set' downloaded
[02/09/08 13:04:34 E] Wrong file signature
[02/09/08 13:04:34 E] Failed to download files
[02/09/08 13:04:34 I] Update source 'http://downloads2.kaspersky-labs.com'
[02/09/08 13:04:37 A] File 'master.xml' downloaded
[02/09/08 13:04:37 A] version: 1220366280
[02/09/08 13:04:41 A] File 'avp.set' downloaded
[02/09/08 13:04:41 E] Wrong file signature
[02/09/08 13:04:41 E] Failed to download files
[02/09/08 13:04:41 E] Update 'Kaspersky Anti-Virus for Mail Servers' failed

Is this message ("Wrong file signature") mean that something is wrong on update servers or on my servers?
Thanks

It will be fixed soon. Please try the update in some hours again.

Thanks a lot...