What does the connection between the PC and the DSL modem look like?  
Ethernet, I hope.  In that case, you can use a "sniffer" program to capture 
a sample of actual traffic on the line.  Do that when it's slow and it may 
be possible to determine if

-  some background process (perhaps spyware/adware/virus; perhaps Skype or 
torrents or P2P...) is using up a lot of your bandwidth

-  some remote system is trying to attack yours

-  something else weird is going on

  Ethereal is a freeware sniffer that can save captured traffic in a format 
spoken by various analysis tools.  If you can capture about 500KB to 1MB of 
traffic, contact me directly and we can arrange for you to send it to me -- 
I have access to commercial tools which can analyze it.

David Gillett


On 26 Jan 2006 at 21:49, Venkat Viswanathan wrote:

> Hi all,
> 
> are computer viruses known to affect internet bandwidth(i have adsl connection)
> or is my ISP pulling a
> fast one.?
> 
> I am supposed to get 51KB/sec but at times it drops down to 6/7 KB/sec(sometimes
> i do get 45/50 KB/sec)
> and my ISP'S response is virus infection.I have AVG free edition and regular
> scan is being done. no virus
> detected but of course it doesn't mean 100% clean since different anti virus
> programs show somewhat
> different results but I am reasonably confident with my AVG scan.
> 
> i also do not notice any slow down of system applications /programs.
> 
> any input will be gratefully acknowledged.
> 
> good day to all----Venkat
> 
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