How do I execute a PowerShell script automatically using Windows task scheduler?

Create the scheduled task and set the action to:

Program/Script: Powershell.exe

Arguments: -File "C:\Users\MyUser\Documents\ThisisMyFile.ps1"

Here is an example using PowerShell 3.0 or 4.0 for -RepeatIndefinitely and up:

# Trigger
$middayTrigger = New-JobTrigger -Daily -At "12:40 AM"
$midNightTrigger = New-JobTrigger -Daily -At "12:00 PM"
$atStartupeveryFiveMinutesTrigger = New-JobTrigger -once -At $(get-date) -RepetitionInterval $([timespan]::FromMinutes("1")) -RepeatIndefinitely

# Options
$option1 = New-ScheduledJobOption –StartIfIdle

$scriptPath1 = 'C:\Path and file name 1.PS1'
$scriptPath2 = "C:\Path and file name 2.PS1"

Register-ScheduledJob -Name ResetProdCache -FilePath $scriptPath1 -Trigger  $middayTrigger,$midNightTrigger -ScheduledJobOption $option1
Register-ScheduledJob -Name TestProdPing -FilePath $scriptPath2 -Trigger $atStartupeveryFiveMinutesTrigger

Instead of only using the path to your script in the task scheduler, you should start PowerShell with your script in the task scheduler, e.g.

C:\WINDOWS\system32\WindowsPowerShell\v1.0\powershell.exe -NoLogo -NonInteractive -File "C:\Path\To\Your\PS1File.ps1"

See powershell /? for an explanation of those switches.

If you still get problems you should read this question.