Cable Modem connection prolems

[nikko]

I have been getting some weird error messages the last couple of days regarding my internet connection. It's been really slow loading web pages, etc. The cable company says that my connection has been solid so the problem is in my computer, possibly in the NIC card. Whenever I run winipcfg and release all and try to renew, it stops responding. It also take forever to post when I restart and I get an error that says Network Protocol 59 Error, whatever that means. Any idea what I'm looking at here? Reformat? Is it possible my NIC card went bad? I've been using the same one for over a year without any problems. Thanks for any help you can pass along.