Perform an IIS Reset on all your SP Servers via PowerShell
This script will list all your SP Servers and restarts IIS on all of them.
add-pssnapin microsoft.sharepoint.powershell
$spserver = get-spserver | ?{$_.role -eq "Application"}
foreach ($server in $spserver)
{
write-host "Performing IIS Reset on Server:"$server.name
iisreset $server.Name
}