Since you "installed 98" would suggest that you update the NIC drivers or uninstall them and then reinstall. Not likely to be a HD problem. Missing files may indicate a conflict with hardware/software, corrupted critical files, malware problem, or possible virus.
Also try ipconfig_release then shut down and reboot do not do a restart. Shut down and reboot will cause the pc to send a request for an IP and see if you pick up the correct IP