Sometimes when we install service packs (1 or2) for windows servers, the servers do not boot up. This happens due to some incompatibilty of the servcie pack with the drivers of some applications or hardware. In such cases we have to go to the recovery console to uninstall them.
1. From recovery console browse to the following director:windows\$NtServicePackUninstall$\spuninst
2. Run Batch spuninst.txt
3. Browse to c;\windows\system32\config
4. ren system system.old
5. ren software software.old
6. ren system.sp system
7. ren software.sp software
8. Reboot the server & the SP will be uninstalled from the registry also.
