c#.Net PowerShell Class

Question

I'm trying to use a PowerShell object with a remote runspace. The initial connection is established, the test returns back with the correct responses, all appears good. I then assign my powershell object some commands to run, and it pops up with the following error message:

System.Management.Automation.PSObjectDisposedException: 'Cannot perform operation because object "PowerShell" has already been disposed. Object name: 'PowerShell'.'

I've not actually disposed of anything (I'd rather keep things open while I'm developing, and optimise it later).

RemoteShell (works fine, no problems):

Private PowerShell RemoteShell (string Hostname, PSCredential psCred)
   {
      PowerShell psCon = PowerShell.Create();
      WSManConnectionInfo connectionInfo = new WSManconnectionInfo
      {
         Port = 5985,
         AuthenticationMechanism = AuthenticationMechanism.Kerberos,
         ComputerName = Hostname,
         Credential= psCred,
         ShellUri = "http://schemas.microsoft.com/powershell/microsoft.powershell",
         IdleTimeout = 99999999
      }

      using (Runspace remoterunspace = RunspaceFactory.CreateRunespace(connectionInfo))
      {
         try {
             remoteRunspace.Open();
             using (psCon) {
                  psCon.Runspace = remoteRunspace;
                  psCon.AddCommand("whoami");
                  psCon.AddStatement().AddScript("[System.Net.Dns]::GetHostByName(($env:computerName))";
                  Collection<PSObject> results= psCon.Invoke();

                  string resultsstr = "Shell created under: " + results[0].ToString() + System.Environment.NewLine + "Shell created on: " + results[1].ToString();
                  AddToOutput(--- not really relevant ---);
          } catch (Exception e) {
                  AddToOutput (--- not really relevant ---);
          }
      }
     return psCon;
   }

JobAsync (dies every time it hits the *** line):

Private Boolean jobAsync (string type, List<ScriptModule>JobList, PSCredential psCred)
{
    PowerShell psCon;
    <type switch kind of irrelevant>
            psCon = RemoteShell(targetFQDN, psCred);


    foreach(ScriptModule curMod in JobList)
    {
        psCon.Commands.Clear();
        List<String[]> ResultsArr = new List<string[]>();
        int TestNum = 0;
        
        foreach(ScriptObject curScr in curMod.moduleScripts)
        {
            << some more irrelevant stuff assembling strings >>

                  **** psCon.AddStatement().AddScript("$param" + pC + " = '" + paramVal + "';"); ****
        }

The **** line constantly generates a PowerShell disposed error exception preventing any further execution. This same code is also used on a local shell (running from the machine the application is running on) and this works fine. The only difference in the code is the remoteShell utilising a runspace...

For reference, here's the localShell code:

private PowerShell LocalShell()
{
    PowerShell psCon = PowerShell.Create();
    try {
        psCon.AddCommand("whoami");
        psCon.AddStatement().AddScript("[System.Net.Dns]::GetHostByName(($env:computerName))");
        Collection<PSObject> results = psCon.Invoke();

        << more irrelevant string stuff >>
    } catch (Exception e) {
       << more irrelevant string stuff >>
    }
  return psCon;
}