Windows vista failed to connect to a network location

Hello everyone, Please I am having issues with connecting a network application, precisely a banking software located on the network, but accessed from different systems. I’ve been able to connect before now- just by clicking on an icon located on the desktop, but pointing to a server from which the application runs. But suddenly, every system with vista OS installed began to fail to connect. What could be wrong? I’ll appreciate a quick response from as many as have an idea. Thanks