Bittorrent (among Other Programs) Error 10051 Fix?

Hi, I've recently noticed that programs such as Bittorrent, Flashfxp, etc. Keep showing me an 'error 10051 Network is unreachable' Does anyone know a good solid fix for this? It worked fine about 5 days ago, but now all of a sudden it stopped working. For the record, i did a system restore to when i believe it was still working, and nothing. Also I had to reinstall my ethernet adapter firmware as for unknown reasons it become disabled and didn't show my LAN under Network Connections, only 1394 Connection.

System Specs

Windows Xp Pro Sp2
1.50 GHz Pentium 4
512 Ram


Any help would be greatly appreciated
Thanks in advance

http://kbase.pscs.co.uk/index.php?article=275

I've looked at that, and obviously my internet connection isn't down or i wouldn't be responding, next I have to routers, My modded xbox has an ip, this computer and my laptop have an ip, and the 360 can connect to live. How do i unblock VPOP3, maybe thats the problem, like i said IDK, thats why im looking for help on here

HERES MY CONNECTION

Modem>Router>PC1
>Router2>PC2(My Desktop)
>Xbox
>Xbox360
>Laptop
So heres how it goes Modem to router1, that router sends internet to PC1 and my router in my room(router 2)
Router 2 sends to xbox, xbox360, laptop and desktop(what im on now)

Hope that made sense, its worked before so i know its possible

Could be a problem with subnets maybe.
Every so often my router will decide to place itself on 255.0.0.0 instead of 255.255.255.248 which means I can't reach anything in the same xxx.yyy.yyy.yyy range. If your router thinks that all addresses within a large range are local, it wont be able to route to them properly.