Powershell script to update Navigation.GlobalIncludeSubSites not applying change

Question

I'm using the following PowerShell script to update the Navigation.GlobalIncludeSubSites value from true to false, which is working, except that the changes are not properly applied.

By that I mean that if I look at the AreaNavigationSettings.aspx page for a site before I run the script I see that "Show subsites" is checked (and the page is showing the wrong menu). After I run the script below, and check that page again, the checkbox is unchecked, but the site is still showing the wrong menu. Only after I click OK on the AreaNavigationSetting.aspx page does the correct menu show up.

As you can see in my code, I am using $pubWeb.Update(), so I'm not sure why the changes aren't being applied without manually clicking OK on each AreaNavigationSettings.aspx page, which defeats the purpose of using the script in the first place.

function ProcessSubWebs($currentWeb)
{       
   foreach($sub in $currentWeb.Webs)
   {
      if($sub.Webs.Count -ge 0)
      {
         Write-Host -ForegroundColor black $sub.Url
         UpdateNavigation($sub)
         ProcessSubWebs($sub)
         $sub.Update()
         $sub.Dispose()
      }            
   }        
}

function UpdateNavigation($web)
{
    $pubWeb = [Microsoft.SharePoint.Publishing.PublishingWeb]::GetPublishingWeb($web)
    Write-Host -ForegroundColor green $pubWeb.Navigation.GlobalIncludeSubSites
    $pubWeb.Navigation.InheritGlobal = $true
    $pubWeb.Navigation.GlobalIncludeSubSites = $false
    $pubWeb.Navigation.GlobalIncludePages = $false
    $pubWeb.Update()
}

ProcessSubWebs(Get-SPWeb -identity http://myserver/site1)
Write-Host -ForegroundColor red "FINISHED"

Any ideas?

[update based on Dave Wise's answer below]

Replace

$pubWeb.Update()

with

$web.AllowUnsafeUpdates = 1;
$web.Update()

worked for me! Thanks Dave :)

Answer 1

Try doing a .AllowUnsafeUpdates = true; prior to the .Update()