This is a useful trick to stop your computer from locking.
Code:
param($minutes = 9999)
write "... screen will be awake for $minutes"
$myshell = New-Object -com "Wscript.Shell"
for ($i = 0; $i -lt $minutes; $i++) {
write "... screen will be awake for" ($minutes-$i)
Start-Sleep -Seconds 60
$myshell.sendkeys("{NUMLOCK}{NUMLOCK}")
}