The patch, announced Monday in security bulletin MS03-007, is incompatible with 12 software fixes for Windows 2000 issued by Microsoft's Product Support Services (PSS) between December 2001 and February 2002. Users running any of those fixes won't be able to reboot their Windows 2000 systems after applying the "critical" patch, according to a revised version of Microsoft's bulletin issued Tuesday.

Customers running Windows 2000 with Service Pack 2 installed should verify the version of a file called "ntoskrnl.exe" on their system before applying the patch. Versions of this file from 5.0.2195.4797 up to and including 5.0.2195.4928 were distributed by PSS and are not compatible with the patch, according to Microsoft.

Users who have an incompatible file on their system need to contact Microsoft PSS before applying the patch. If the patch is installed on a system with the incompatible file, the machine will fail on the first reboot and will have to be recovered using the Windows 2000 recovery console, Microsoft said.