Windows Event ID 1066 – WinLogon: Session Manager Subsystem Initialization

Start by examining the complete Event ID 1066 details to understand the initialization context and timing.

1. Open Event Viewer by pressing Win + R, typing eventvwr.msc, and pressing Enter
2. Navigate to Windows Logs → System
3. Filter the log by clicking Filter Current Log in the Actions pane
4. Enter 1066 in the Event IDs field and click OK
5. Double-click the most recent Event ID 1066 entry to view detailed information
6. Note the timestamp, computer name, and any additional data in the event description
7. Compare the timestamp with other boot events like Event ID 12 (kernel boot) to assess initialization timing

Use PowerShell to retrieve recent Event ID 1066 occurrences:

Get-WinEvent -FilterHashtable @{LogName='System'; Id=1066} -MaxEvents 10 | Select-Object TimeCreated, Id, LevelDisplayName, Message

Correlate Event ID 1066 with other boot events to assess overall system startup performance and identify potential bottlenecks.

1. Use PowerShell to gather comprehensive boot event data:

# Get boot sequence events including Event ID 1066
$BootEvents = @(12, 1066, 6005, 6009)
Get-WinEvent -FilterHashtable @{LogName='System'; Id=$BootEvents; StartTime=(Get-Date).AddDays(-7)} | Sort-Object TimeCreated | Select-Object TimeCreated, Id, LevelDisplayName, Message

2. Calculate the time difference between kernel boot (Event ID 12) and Session Manager initialization (Event ID 1066):

# Calculate Session Manager initialization time
$KernelBoot = Get-WinEvent -FilterHashtable @{LogName='System'; Id=12} -MaxEvents 1
$SessionMgr = Get-WinEvent -FilterHashtable @{LogName='System'; Id=1066} -MaxEvents 1
$InitTime = ($SessionMgr.TimeCreated - $KernelBoot.TimeCreated).TotalSeconds
Write-Host "Session Manager initialization took: $InitTime seconds"

3. Review the calculated timing against baseline performance metrics
4. Document any significant delays (typically over 60 seconds indicates issues)

Examine the Session Manager process (SMSS.exe) and related system processes to ensure proper initialization and ongoing health.

1. Verify SMSS.exe process status using PowerShell:

# Check Session Manager process details
Get-Process -Name "smss" -ErrorAction SilentlyContinue | Select-Object Name, Id, StartTime, WorkingSet, PagedMemorySize

2. Examine critical system processes created by Session Manager:

# Verify essential processes initialized by Session Manager
$CriticalProcesses = @("csrss", "wininit", "winlogon")
foreach ($proc in $CriticalProcesses) {
    Get-Process -Name $proc -ErrorAction SilentlyContinue | Select-Object Name, Id, StartTime
}

3. Check Session Manager registry configuration:

# Examine Session Manager registry settings
Get-ItemProperty -Path "HKLM:\SYSTEM\CurrentControlSet\Control\Session Manager" | Select-Object BootExecute, PendingFileRenameOperations

4. Review system event logs for any Session Manager related errors or warnings
5. Use Task Manager → Details tab to verify SMSS.exe is running with appropriate privileges

When Event ID 1066 appears delayed or is missing, perform comprehensive boot analysis to identify underlying causes.

1. Enable boot logging to capture detailed startup information:

# Enable boot logging (requires restart)
bcdedit /set bootlog yes

2. Use Windows Performance Analyzer (WPA) or built-in tools to analyze boot performance:

# Generate boot performance report
xperf -on PROC_THREAD+LOADER+PROFILE -stackwalk Profile -BufferSize 1024 -MaxFile 256 -FileMode Circular

3. Check for pending file operations that might delay Session Manager:

# Check for pending file rename operations
$PendingOps = Get-ItemProperty -Path "HKLM:\SYSTEM\CurrentControlSet\Control\Session Manager" -Name "PendingFileRenameOperations" -ErrorAction SilentlyContinue
if ($PendingOps) {
    Write-Host "Pending file operations detected:"
    $PendingOps.PendingFileRenameOperations
}

4. Examine system file integrity:

# Run system file checker
sfc /scannow

5. Review hardware event logs for potential issues affecting boot performance
6. Disable boot logging after analysis:

# Disable boot logging
bcdedit /set bootlog no

Perform advanced diagnostics when Event ID 1066 issues persist or indicate deeper system problems.

1. Create a comprehensive boot event timeline:

# Create detailed boot analysis script
$StartTime = (Get-Date).AddHours(-2)
$BootEvents = Get-WinEvent -FilterHashtable @{LogName='System'; StartTime=$StartTime} | Where-Object {$_.Id -in @(12, 13, 1066, 6005, 6009, 6013)} | Sort-Object TimeCreated

foreach ($event in $BootEvents) {
    Write-Host "$($event.TimeCreated) - Event ID $($event.Id): $($event.LevelDisplayName)"
}

2. Examine Session Manager memory dumps if available:

# Check for memory dump files
Get-ChildItem -Path "C:\Windows\Minidump\" -Filter "*.dmp" | Sort-Object LastWriteTime -Descending | Select-Object -First 5

3. Analyze registry hive loading performance:

# Check registry hive sizes and modification times
$HiveFiles = @("SYSTEM", "SOFTWARE", "SECURITY", "SAM", "DEFAULT")
foreach ($hive in $HiveFiles) {
    $hivePath = "C:\Windows\System32\config\$hive"
    if (Test-Path $hivePath) {
        $hiveInfo = Get-Item $hivePath
        Write-Host "$hive hive: Size=$([math]::Round($hiveInfo.Length/1MB,2))MB, Modified=$($hiveInfo.LastWriteTime)"
    }
}

4. Enable Session Manager debug logging (advanced):

# Enable Session Manager debugging (requires restart)
Set-ItemProperty -Path "HKLM:\SYSTEM\CurrentControlSet\Control\Session Manager\Debug" -Name "DebugFlags" -Value 0x00000001 -Type DWord -Force

5. Review Windows Error Reporting for Session Manager crashes:

# Check for Session Manager related error reports
Get-WinEvent -FilterHashtable @{LogName='Application'; ProviderName='Windows Error Reporting'} -MaxEvents 50 | Where-Object {$_.Message -like "*smss*"}