Powershell : this command sticks my script, freezes

Question

I am trying to get a list of available updates using

$UpdateSession = New-Object -ComObject 'Microsoft.Update.Session'
Write-Host "[1]"

$UpdateSession.ClientApplicationID = 'MSDN PowerShell Sample'
Write-Host "[2]"

$UpdateSearcher = $UpdateSession.CreateUpdateSearcher()
Write-Host "[3]" 

$SearchResult = $UpdateSearcher.Search("IsInstalled=0 and IsHidden=0")
Write-Host "[4]"

The last instruction $SearchResult = $UpdateSearcher.Search("IsInstalled=0 and IsHidden=0") freezes, returns nothing and I can't figure out why.
Output :

[1]
[2]
[3]
<running...>

I assume it is actually doing something because I can't CTRL+C to stop it. Have to re-start Powershell.

(W7 SP1, .NET Framework 4.6.1, Powershell 4.0)

Any idea ?

Edit: took those lines from the Get-WindowsUpdates.ps1 script