Lags every four seconds

Up until last night for some reason FFXI has been lagging on my PC. Turns out it lags for about a second every four seconds. Any one have any idea on to why it is doing that?

-I've checked FFXI files and everything was good.
-Checked to see if some how I got a virus and I'm clear of that.
-Reseted my modem and wireless router and still hasn't fixed. (netgear wireless-G)
-Could it be that my PC is finally giving out? its about five years old.
-Doesn't happen when i use other programs.

I'm about to travel to get my laptop and reinstall ffxi to see if the issue is the net or the PC

fjamesfernandez,

We can offer a few suggestions if you are experiencing any of the following:
• Have difficulty connecting to or staying connected to the PlayOnline Viewer or FINAL FANTASY XI
• Crash, receive a black screen error, or get stuck at the downloading data screen upon clicking your character handle or character select button
• See your the lag meter turn red
• Encounter increased lag or connection problems near crowed areas
• Have trouble accessing specific zone(s)
• Have trouble logging in with specific character(s)
• Receive any of these errors: 3113, 3100, 4001, 1160

Suggestions:
1. Check to make sure you have properly configured or turned off any of the following: Routers, Proxy Servers, NAT Servers, Internet Connection Sharing services.
2. If you are using any kind of software/hardware Internet Sharing service/device the following ports need INCOMING access to your PC: TCP 1024 - 65535, UDP 53, and 50000 - 65535. Also, check to make sure that the ports mentioned are not blocked by your ISP for INCOMING access. Proper configuration of any of the above items mentioned should be done by following the instructions in the software/hardware manual or calling the manufacturer's technical support.
3. If you are using a router, and have configured that router for port forwarding, temporarily bypass that router and connect directly to the modem.

Please take note of the following:
• Proxy servers, and satellite connections are not supported and do not work correctly with FINAL FANTASY XI.
• Your router may require that you use a PC to configure your network settings. For more information about how to configure your network settings, please refer to the instruction manual that came with your router or contact the manufacturer directly.
• If your Internet Service Provider (ISP) specifies a DNS server, you need to make sure to configure your settings to allow packets to pass through UDP Port 53 as well. For more information, please refer to the instruction manual for your router or the information provided by your ISP.