In Windows Server 2008 R2 environments using roaming profiles with Windows 7 clients, simultaneous user logins create notorious "last writer wins" conflicts. Each session overwrites changes from other active sessions, particularly problematic in environments where users maintain multiple concurrent logins.

Microsoft's background upload feature (introduced in Windows 7/Server 2008 R2) attempts to address this by:

// Sample registry setting for background upload
HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\System
"UploadRoamingProfile"=dword:00000001

However, this merely delays rather than solves the conflict problem. Profile changes still eventually overwrite each other during synchronization.

For environments where mandatory logoffs aren't feasible, consider these technical approaches:

1. Granular Folder Redirection

Implement strategic folder redirection to minimize profile conflicts:

# PowerShell script to configure folder redirection
Set-ItemProperty "HKCU:\Software\Microsoft\Windows\CurrentVersion\Explorer\User Shell Folders" -Name "Desktop" -Value "\\server\share\%username%\Desktop"
Set-ItemProperty "HKCU:\Software\Microsoft\Windows\CurrentVersion\Explorer\User Shell Folders" -Name "My Documents" -Value "\\server\share\%username%\Documents"

2. Scheduled Profile Synchronization

Create a scheduled task that periodically forces profile uploads:

<?xml version="1.0" encoding="UTF-16"?>
<Task version="1.2" xmlns="http://schemas.microsoft.com/windows/2004/02/mit/task">
  <Triggers>
    <TimeTrigger>
      <Repetition>
        <Interval>PT30M</Interval>
      </Repetition>
      <StartBoundary>2023-01-01T08:00:00</StartBoundary>
      <Enabled>true</Enabled>
    </TimeTrigger>
  </Triggers>
  <Actions Context="Author">
    <Exec>
      <Command>powershell.exe</Command>
      <Arguments>-Command "Start-Process -FilePath 'rundll32.exe' -ArgumentList 'keymgr.dll,KRShowKeyMgr'"</Arguments>
    </Exec>
  </Actions>
</Task>

When native solutions prove insufficient, consider these enterprise options:

• FSLogix Profile Containers (now Microsoft-owned)
• Liquidware ProfileUnity
• Citrix User Profile Management

Each offers unique approaches to profile conflict resolution, with FSLogix being particularly effective through its container-based approach that mounts the entire profile as a VHD.

For minimal conflicts, implement this hybrid approach:

1. Redirect all volatile folders (Documents, Desktop, etc.)
2. Use mandatory profiles for static configuration
3. Implement Group Policy for conflict resolution:

// GPO settings for improved roaming profiles
Computer Configuration\Policies\Administrative Templates\System\User Profiles
"Set roaming profile path for all users logging onto this computer" = Enabled
"Delete cached copies of roaming profiles" = Enabled
"Only allow local user profiles" = Disabled

In enterprise Windows environments with roaming profiles, we frequently encounter scenarios where users maintain multiple active sessions across different workstations. The fundamental technical issue stems from how NTUSER.DAT handles file locks during profile synchronization.

// Sample PowerShell to detect concurrent sessions
Get-WmiObject -Class Win32_ComputerSystem | ForEach-Object {
    $loggedOnUsers = $_.UserName
    if ($loggedOnUsers -match "\\") {
        $domainUser = $loggedOnUsers.Split('\')[1]
        $activeSessions = quser | Where-Object { $_ -match $domainUser }
        if ($activeSessions.Count -gt 1) {
            Write-Host "Concurrent session detected for $domainUser"
        }
    }
}

The Windows Client-Side Extension (CSE) for folder redirection operates with these technical constraints:

• NTUSER.DAT requires exclusive access during load/unload
• Background uploads still follow last-writer-wins semantics
• Registry hive flushing occurs at 15-minute intervals by default

After extensive testing across multiple client deployments, these approaches showed promise:

# Group Policy adjustment for slower profile sync
Set-GPRegistryValue -Name "Roaming Profile Settings" -Key "HKLM\SOFTWARE\Policies\Microsoft\Windows\System" 
-ValueName "UploadRoamingProfile" -Type DWord -Value 2

For environments requiring near-real-time sync, consider this registry tweak:

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\System]
"BackgroundUploadRoamingProfile"=dword:00000001
"BackgroundUploadThrottlingDelay"=dword:0000003c

When native Windows solutions fall short, these commercial options have proven effective in production:

• Liquidware ProfileUnity: Implements delta synchronization with conflict resolution rules
• FSLogix: Container-based approach that eliminates traditional profile conflicts
• Citrix UPM: Active write-back prevention with exclusion lists

For new deployments, these design patterns can prevent concurrent session issues:

// Example DSC configuration for optimized profile handling
Configuration RoamingProfileOpt {
    Node "SERVER01" {
        WindowsFeature FS-FileServer {
            Ensure = "Present"
            Name = "FS-FileServer"
        }
        
        File ProfileShare {
            Ensure = "Present"
            DestinationPath = "D:\Profiles"
            Type = "Directory"
        }
        
        SmbShare ProfileShareConfig {
            Ensure = "Present"
            Name = "Profiles$"
            Path = "D:\Profiles"
            FullAccess = "DOMAIN\Domain Users"
            EncryptData = $true
        }
    }
}