Microsoft on Thursday gave early warning that next week's monthly dose of security bulletins and patches will be among its biggest ever.

According to the Advance Notification service, which pre-announces upcoming patches but limits the information disclosed, next Tuesday's roundup will include 13 security bulletins, at least three of which will be marked "Critical" the Redmond, Wash.-based developer's most dire warning.

Nine of the bulletins affect Microsoft Windows. That's a much-higher-than-normal number, and three times what the company published in January.

Other patches will be published to fix bugs in SharePoint Services, Microsoft Office, the .Net Framework, Visual Studio, Windows Media Player, and MSN Messenger.

Microsoft has several unresolved vulnerabilities, according to security researchers, who have noted problems in Windows XP SP2's buffer overflow defense, and continued weaknesses in Internet Explorer.

The patches will be posted on Microsoft's security Web site on February 8, and be available for downloading from the Windows Update service that same day.