If there are other similarly configured workstations on the same network that are NOT experiencing this problem, then it's probably a misconfiguration on that one workstation. What that misconfiguration might be is anyone’s guess since there’s so little to work with here. But the first thing I would do is use IPCONFIG and compare its TCP/IP configuration to 2-3 other computers that are functioning normally.
To generate a TCP/IP dump,
Go to Start->Run, type "cmd" (no quotes), and hit enter. In the command window, type "ipconfig /all > temp.txt" (no quotes) and post the file's contents here.