diff --git a/Scripts/GUI/Show-MainWindow.ps1 b/Scripts/GUI/Show-MainWindow.ps1
index 035f906..d27bd15 100644
--- a/Scripts/GUI/Show-MainWindow.ps1
+++ b/Scripts/GUI/Show-MainWindow.ps1
@@ -1283,7 +1283,7 @@ function Show-MainWindow {
                 $appRemovalScopeCombo.SelectedIndex = 0
             }
             1 { 
-                $userSelectionDescription.Text = "Changes will be applied to a different user profile on this system. Note: changes may not apply correctly if the target user is currently logged in."
+                $userSelectionDescription.Text = "Changes will be applied to a different user profile on this system."
                 $otherUserPanel.Visibility = 'Visible'
                 $usernameValidationMessage.Text = ""
                 # Hide "Current user only" option, show "Target user only" option
@@ -1353,13 +1353,13 @@ function Show-MainWindow {
         $successBrush = $window.Resources['ValidationSuccessColor']
 
         if ($username.Length -eq 0) {
-            $usernameValidationMessage.Text = "[X] Please enter a username"
+            $usernameValidationMessage.Text = "Please enter a username"
             $usernameValidationMessage.Foreground = $errorBrush
             return $false
         }
         
         if ($username -eq $env:USERNAME) {
-            $usernameValidationMessage.Text = "[X] Cannot enter your own username, use 'Current User' option instead"
+            $usernameValidationMessage.Text = "Cannot enter your own username, use 'Current User' option instead"
             $usernameValidationMessage.Foreground = $errorBrush
             return $false
         }
@@ -1367,12 +1367,18 @@ function Show-MainWindow {
         $userExists = CheckIfUserExists -Username $username
 
         if ($userExists) {
-            $usernameValidationMessage.Text = "[OK] User found: $username"
+            if (TestIfUserIsLoggedIn -Username $username) {
+                $usernameValidationMessage.Text = "User '$username' is currently logged in. Please sign out that user first."
+                $usernameValidationMessage.Foreground = $errorBrush
+                return $false
+            }
+
+            $usernameValidationMessage.Text = "User found: $username"
             $usernameValidationMessage.Foreground = $successBrush
             return $true
         }
 
-        $usernameValidationMessage.Text = "[X] User not found, please enter a valid username"
+        $usernameValidationMessage.Text = "User not found, please enter a valid username"
         $usernameValidationMessage.Foreground = $errorBrush
         return $false
     }
@@ -1515,7 +1521,13 @@ function Show-MainWindow {
     $deploymentApplyBtn = $window.FindName('DeploymentApplyBtn')
     $deploymentApplyBtn.Add_Click({
         if (-not (ValidateOtherUsername)) {
-            Show-MessageBox -Message "Please enter a valid username." -Title "Invalid Username" -Button 'OK' -Icon 'Warning' | Out-Null
+            $validationMessage = if (-not [string]::IsNullOrWhiteSpace($usernameValidationMessage.Text)) {
+                $usernameValidationMessage.Text
+            }
+            else {
+                "Please enter a valid username."
+            }
+            Show-MessageBox -Message $validationMessage -Title "Invalid Username" -Button 'OK' -Icon 'Warning' | Out-Null
             return
         }
 
diff --git a/Scripts/Helpers/TestIfUserIsLoggedIn.ps1 b/Scripts/Helpers/TestIfUserIsLoggedIn.ps1
new file mode 100644
index 0000000..9c0d759
--- /dev/null
+++ b/Scripts/Helpers/TestIfUserIsLoggedIn.ps1
@@ -0,0 +1,42 @@
+function TestIfUserIsLoggedIn {
+    param(
+        [Parameter(Mandatory)]
+        [string]$Username
+    )
+
+    try {
+        $quserOutput = @(& quser 2>$null)
+        if ($LASTEXITCODE -ne 0 -or -not $quserOutput) {
+            return $false
+        }
+
+        foreach ($line in ($quserOutput | Select-Object -Skip 1)) {
+            if ([string]::IsNullOrWhiteSpace($line)) { continue }
+
+            # Remove current-session marker and split columns.
+            $normalizedLine = $line.TrimStart('>', ' ')
+            $parts = $normalizedLine -split '\s+'
+            if ($parts.Count -eq 0) { continue }
+
+            $sessionUser = $parts[0]
+            if ([string]::IsNullOrWhiteSpace($sessionUser)) { continue }
+
+            # Normalize possible DOMAIN\user or user@domain formats.
+            if ($sessionUser.Contains('\')) {
+                $sessionUser = ($sessionUser -split '\\')[-1]
+            }
+            if ($sessionUser.Contains('@')) {
+                $sessionUser = ($sessionUser -split '@')[0]
+            }
+
+            if ($sessionUser.Equals($Username, [System.StringComparison]::OrdinalIgnoreCase)) {
+                return $true
+            }
+        }
+    }
+    catch {
+        return $false
+    }
+
+    return $false
+}
diff --git a/Win11Debloat.ps1 b/Win11Debloat.ps1
index 270a47d..b39b022 100644
--- a/Win11Debloat.ps1
+++ b/Win11Debloat.ps1
@@ -278,6 +278,7 @@ if (-not $script:WingetInstalled -and -not $Silent) {
 . "$PSScriptRoot/Scripts/Helpers/GetTargetUserForAppRemoval.ps1"
 . "$PSScriptRoot/Scripts/Helpers/GetUserDirectory.ps1"
 . "$PSScriptRoot/Scripts/Helpers/GetUserName.ps1"
+. "$PSScriptRoot/Scripts/Helpers/TestIfUserIsLoggedIn.ps1"
 
 # Threading functions
 . "$PSScriptRoot/Scripts/Threading/DoEvents.ps1"