With mine connection (1024/320) it's when emule is running and I have no upload-limit set in emule (see preferences) my internet is really slow (surfing/mailing/chatting).
With my connection the maximum (theoretical) upload is about 40 kb/sec,allthough it's in real around 30/31 that emule uses.
But then my bandwidth for surfing is very narrow.On the 2nd PC too (which is connected through a router).
When I set an upload-limit in emule (and in my case I set it on 24 kb/sec) it's all running smoothly.
So at night and during the day it is without limit and from about we all get home here I set the limit so we can all use the 2 pc's.
Maybe it's all old news for you,but it's an idea anyway
Btw : I do have to restart my router/modem every week or so because then the things you describe are happening anyway.
But that has something to do with the max. connections the router
can make (so I've been told).
When it's restarted (router only,not the pc) then it's OK again.
So if you're on a router that's another idea too !
But it's sounds like it's the upload-limit you have to set in emule.
Greetz,
Kareltje538