FTP, DNS failures

[vityav]

Hello,
I've been living with this issue for a while but it's finally starting to be a serious problem. For the past month or so, all FTP capabilities of my computer have been failing. I can't access public FTP servers, local FTP hosts, I can't even access my own computer via the loopback address. Nor can anybody else access my computer. I can see my apache server, as can others, but no file sharing (even with VPN programs such as Hamachi)
My other problem is with my DNS. It periodically (every 10 minutes or so) dies for about a minute. I can still access web pages with their IP address but no luck with DNS. I don't have many connections open (that I'm aware of), no file sharing programs, nothing like that. I've tried flushing the DNS cache with no luck either, but the problem goes away after a minute and DNS capabilities continue as normal.
Any help you could provide would be greatly appreciated,
Vitya