dumpy

I have installed Windows 2003 Server and tweaked it to act as a workstation. All works well except that when I open a folder in the left pane of Windows Explorer there is quite a long delay in displaying the contents in the right pane. The more contents the longer delay. At times it even stops responding. This does not happen when I display drive contents. Any ideas or suggestion? Thanks P4 2.4 ghz 768mb DDR 2100