1.Error in CONFIG.SYS line XX
2.evice / Service has failed to start
3.Failure to start GUI
1. Check for syntax errors in CONFIG.SYS and that the files (c:\windows\himem.sys, c:\windows\emm386.exe. c:\windows\setver.exe) it references actually exist and are not corrupted.
2. Determine which Device or Service has failed to start, and whether that is because the associated files are missing or corrupted.
3. Re-install Windows with Repair option, then use WindowsUpdate to repair security holes.