Solve : lost broadband/internet connections?

i have a dell dimension pc.We use broadband and can use dial up.Everything worked untill last thursday23/02 when the broadband dissapeared.When trying to connect the computer said no dialtone.We tried dial up and instead of connecting at 39bps it connected at 4 then disconnected.The broadband connection is fine as I am using it now on another pc.We put in a webcam the previous week and all worked well any suggestions?Do you use a broadband modem or a router? Who is your ISP?adsl modem the isp is tesco  (in the uk)Is it a Sagem, Voyager or a Speedtouch modem?
Is the ADSL light on the modem solid green? Are your filters correctly fitted?

I buy beans from Tesco.... I buy my internet provision from an internet SERVICE provider.the modem is an adsl speedtouch 300 when the modem is connected to the dell one light is gard green the other marked adsl is flashing.
at this time I am on an old pc and the light is hard green

tesco beans give me windforgot the filters must be right as I am on broadband nowUnplug everything from the USB sockets except the modem. Does it train to the DSL signal now?
If it does, your USB sockets aren't providing enough power for the items you have attached. Either buy a USB add-in card or leave something unplugged.

If it doesn't, reinstall the modem. A good tip here is to use the extended REACH drivers.
it cannot be the usb I have disconnected everything and it still does not connect worked fine b4 then stopped and this does not explain why the dial up has gone so slow.Is there a virus that gets arround the security that stops connections?If the DSL light is flashing then it's not syncing. Lack of sync is an exchange, line or modem PROBLEM. As the modem works fine on a different machine but the same connection linewise then it must be a driver or component on the affected machine that's to blame. Have you recently updated any chipset drivers, by Windows Update perhaps? Is there a reasonable restore point available?
If your dialup is slow with the Speedtouch plugged in then that points to a faulty modem, perhaps caused by lack of power.
The modem takes only minutes to reinstall and it's the first thing that Tesco "support" will tell you to do after checking filters etc.
You can post a HijackThis LOG if you like but I've never heard of malware that causes a USB DSL modem not to sync.we have reinstalled the drivers for the modem got new ones from tesco support.I have taken out the modem and then used dial up still slow.How do I system restore? or better still whre do I find it.The microsoft update is set on auto  so I would not know
Try the drivers that I pointed you to. To launch System Restore, enter
%SystemRoot%\system32\restore\rstrui.exe
in the Start>Run box. Choose "Restore My Computer To An Earler Time" and choose a date prior to your problems occurring.
Is dialup still slow if the DSL modem is removed from the equation?the dial up is slow with the modem in or out it is very strange
It sounds like a line fault (Internal or external, including filters) but the FACT that another system works from exactly the same wiring (You are connecting to exactly the same point via the same filter aren't you?) belies this.