Are you using a standard analoge modem (56k dial-up) or are you on a digital connection like broadband ADSL ? A standard modem may be affected in this way by a poor quality analogue phone line, in which case you can ask your phone provider to boost the "gain" on the line, which basically just means "can I have a better signal please?" !

When you are connected to the Internet, you may have a little flashing icon of two computers connected in the System Tray (bottom-right corner of the screen down by the clock). If you do, hover the mouse over it and see if it gives you a connection speed (e.g. 40.0kpbs or 40,000bps). Let us know what it says.

Does your modem cut-off after you've not used it for a few minutes? Most dial-up connections will, by default, turn off after 20 minutes of "inactivity" and these can be changed to a different amount of time. If your Internet connection cuts off whilst you are loading different web pages, then this isn't the problem.

Does the Internet connection tend to cut off when you are downloading files or does it do it when you are just browsing web pages normally?

Does the Internet connection cut off when you open other applications or switch to your email program to send and receive messages? Just wondering whether it can't multi-task very well - do you know PC spec is, e.g. what processor you've got and how much memory is fitted?

Finally, what version of Windows are you running? Windows 95, 98, ME, 2000 or XP ?

Sorry to answer your question with a load more questions but there isn't just one answer for it. If you can come back to us with some more detail in answering my points above, we can probably come up with a list of suggestions for you