Network Connectivity Issues

I have a Notebook running XP Pro. and when it was put on my small business
network, it was able to reach our server (filesharing, print server only)
without issue when network drives were originally mapped. One week later,
the network drives are not mapped and can not be mapped - can not even ping
the server but I can connect to the internet? This system was connected to
Fast Ethernet Switch but I connected this directy to my DSL Gateway Router to
see if this would help. I can still connect to the internet but can not
"see" the server? The DSL Router is connected to the server. All other XP
Pro. desktop systems can access the server. Help please....
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Jeffrey Gavlinski