File server dropping drive connections

Hi

I have a rebuilt windows 2003 fileserver that keeps dropping network drive connections. The server used to be our PDC/fileserver/WSUS server etc but after a RAID issue I have had to flatten it and start again. I have all the data files back on it and configured it as a fileserver only. The issue is if I connect to a network share and drill through a folder or 2 when I try and go back or go into another folder I get a delay then an error stating that there was an error reconnecting drive n:

Any ideas?