There could be a hardware problem with the enet adpater, but you should reinstall it just in case. You should remove any entry for enet adapters in Device Manager, and then go through the procedure for reinstalling the enet adapter. I have written a Knowledge Base that details how to do this, KB 2HLC95UK. You can search for this KB ID on our main site, or try this link to the page:
Beyond that, I would recommend calling our support lines so that we can try troubleshooting with you further. Ultimately, a repair may be necessary.