I got this from another site and it appears to be for Windows 2003, don't know if it will work in 2008, use at your own risk.
CODE
To disable shutdown tracker:
Windows Registry Editor Version 5.00
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Reliability]
"TimeStampInterval"=dword:00000000
"ShutdownReasonUI"=dword:00000000
"ShutdownDoStateSnapshot"=dword:00000002
To enable shutdown tracker:
Windows Registry Editor Version 5.00
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Reliability]
"TimeStampInterval"=dword:00000000
"ShutdownReasonUI"=dword:00000001
"ShutdownDoStateSnapshot"=dword:00000002
Windows Registry Editor Version 5.00
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Reliability]
"TimeStampInterval"=dword:00000000
"ShutdownReasonUI"=dword:00000000
"ShutdownDoStateSnapshot"=dword:00000002
To enable shutdown tracker:
Windows Registry Editor Version 5.00
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Reliability]
"TimeStampInterval"=dword:00000000
"ShutdownReasonUI"=dword:00000001
"ShutdownDoStateSnapshot"=dword:00000002
