I am trying to execute:

$run = "Timber"
$workspace = "C:\jenkins.workspaces"
try
{
Write-Output "Removing the log file ($workspace\trunk\Poirot_ESA_Jenkins_temp\$run.log)"
if (Test-Path("$workspace\trunk\Poirot_ESA_Jenkins_temp\$run.log"))

}
catch

c:_femenv\psexec
jen-trunk -i 2 $env:SystemRoot\system32\WindowsPowerShell\v1.0\powershell.exe -File "$workspace\trunk\Poirot_ESA\$run.ps1"

try
{
Write-Output "Seaching for a new log file ($workspace\trunk\Poirot_ESA_Jenkins_temp\$run.log)"
if (Test-Path("$workspace\trunk\Poirot_ESA_Jenkins_temp\$run.log"))

}
catch
{
Write-Output "The file $workspace\trunk\Poirot_ESA_Jenkins_temp\$run.log doesn't exist. The run is marked as failure."
break
}

The red line is causing a problem. The PSEXE tool can't establish PSEXE service because the lack of admin privileges. If I run the hudson script in same way like the plugin does from powershell with elevated privileges, everything works fine. If build the job in Jenkins, PSEXE fails. If use a cmd execution, it works but from other reasons, I can't use is permanently.
The strange thing is that this script worked before and as far as I know, nothing change since the last working state.