It's "tcp/ip". And yeah, I think you'd want to reinstall windows.
This sounds like it could be:
- a virus/worm
- a disk error
So just installing might not fix it. I'd back up your files before you do anything, then wipe the disk and reinstall.
Make sure your virus checker is up to date, as you might re-infect yourself from your data disks.
If it's a disk error, your hard drive might be failing, and you'll want to run some sort of disk check utility. You might need to buy a new drive, in the long run.
How did the problem start?