PS: Working with balloon tips

Question

I have a Powershell function that shows a balloon tip and it works fine, except for two things. First, is there a way to have my script display a message to every logged-in user? 
Second, according to several blog posts (like this and this),
I should be cleaning up my icon. The sample code doesn't seem to work for me. Regardless of how I click the balloon, the icon says in place. If I hover my mouse over the icon (with or without closing the balloon), the icon disappears. Am I missing something
here?
Thanks.
Function Start-LogoffNotice {
<#
.SYNOPSIS
Displays a notice in the Windows notification area.
#>
param (
$IconPath = (Get-Process -id $pid | Select-Object -ExpandProperty Path),
[ValidateSet("Info","Warning","Error","None")]
$BalloonIcon,
$BalloonText,
$BalloonTitle,
$BalloonTimeout = "60000"
Add-Type -AssemblyName System.Windows.Forms | Out-Null
$objNotifyIcon = New-Object System.Windows.Forms.NotifyIcon
$objNotifyIcon.Icon = [System.Drawing.Icon]::ExtractAssociatedIcon($IconPath)
$objNotifyIcon.BalloonTipIcon = $BalloonIcon
$objNotifyIcon.BalloonTipText = $BalloonText
$objNotifyIcon.BalloonTipTitle = $BalloonTitle
$objNotifyIcon.Visible = $True
$objNotifyIcon.ShowBalloonTip($BalloonTimeout)
#This section doesn't seem to do anything.
Register-ObjectEvent -InputObject $objNotifyIcon -EventName BalloonTipClosed -Action {
Unregister-Event $objNotifyIcon.SourceIdentifier
Remove-Job $objNotifyIcon.Action
$objNotifyIcon.Dispose()
} | Out-Null
Start-LogoffNotice -BalloonIcon "Info" -BalloonText "You will be logged off in 1 minute. Please save your work." -BalloonTitle "Logoff Notice"

Answer 1

Regarding your second question, you need you make sure the $objNotifyIcon.Dispose() method is being run. That's the piece that will remove the icon from the Notification Area. Perhaps you can copy it from the section that indicates it doesn't do anything
and paste it underneath $objNotifyIcon.ShowBalloonTip($BalloonTimeout). If it disposes right away, then you may need to add a Start-Sleep command between the two, such as Start-Sleep -Milliseconds $BalloonTimeout.
Edit: Rewording for clarity.