On opening Gant chart using PTGantChart.ocx control on a network (client m/c), the page crashes giving an Object Not set to reference error and parent pages also crashes. Though the same code with data executes successfully on the server.
Although not entirely sure that this is your problem the policies for loading and executing applications in non full trust locations (the internet, or a network share) can be restricted by your network administrator. Maybe your administrator has restricted windows from loading unsigned ocx’s from partly trusted locations? You can sign the ocx’s with third party tools.
On the other hand, the ActiveX control must be registered on the client computer with regsvr32 to function, and if you register it on a network share it will get the network path in the registry. If your network path changes (sometimes X:\aaa and sometimes Y:\aaa) that could be an explanation.