Some security-minded administrators who tinkered with their operating systems to better protect their desktops had an unwelcome surprise in last week's patch release from Microsoft.

A buggy patch, which was sent out as part of Microsoft's October patch release, has some users scrambling to fix the trouble it caused. Microsoft has acknowledged that there have been problems with Windows 2000 systems, Windows XP, Windows Server 2003 and Windows 2000 Server.

Users reportedly started having problems within a day of the patch release, which was Tuesday, Oct. 11.

Microsoft has reported that the flawed patch could lock users out of their PC, prevent the Windows Firewall from starting, block applications, and empty the network connections folder.

The company posted a document on its Website noting that the problems affect users who have changed the default permission settings of the COM+ catalog, which are files in the %windir%/registration folder.

''Yes, we are aware of some of the information floating around about problems after installing the MS05-051 update on Windows 2000 systems,'' wrote Mike Reavey on the Microsoft Security Response Center's blog.

To fix the problems, Microsoft is advising users to 'restore the default permissions to the COM+ catalog'. The steps to do this can be found at this Website.

The patch that's causing all this trouble was released to fix four Windows vulnerabilities that Microsoft called 'critical'. The upate was sent out in Security Bulletin MS05-051.

September's patch release didn't come out at all, with Microsoft saying there were unresolved problems with it.