mxstartup is responsible for some very initial system checks, loading the S: drive, and handing over to mxmaster.exe.

The S: drive is a TrueCrypt partition. Its keyfile is located in an ADS at C:\System\Execute\DLL:SystemKeyFile, and the password is segahardpassword.

Micetools contains a bare-minim version of this file. It can be found on the micetools repository. This shows, roughly, how the volume is mounted and prepared.

This is the first time anything other than the Windows XP boot screen will be shown.

mxstartup is responsible for a number of error codes, listed below. This table contains every error mxstartup can produce, to the best of my knowledge.

Error code Message Meaning
0500 SecurityCheck error
0501 CheckEwfState error
0502 GetSystemVersion error
0503 GetsystemKeyFile
0504 SetDiskAccessPrivilege
0505 MountSystem
0506 MountUpdate error
0507 ExecuteMaMaster
0508 GetOSUpdateKeyFile error
0509 ExecuteMxOSUpdate error
0510 ChangeEWFStateEnable error
0511 GetSBRSlotOSState error
0512 Deleate Key File error
0513 MountDriver error
0514 CheckPlatform error
0540 Unmount error
0541 MountRecoveryVolume error
0543 MxChangeActivePartition error
0545 osuSystemReboot error
0546 GetSystemDiskNumber error
???? SetBackupComputerName failed

These errors are also reported into the Application event log, under the source mxstartup.