Modem access

[#1]

I found that I couldn't access my speedtouch 780WL via the browser but could browse the internet ok. A reboot sorted this out but after a few hours I lost access again. I swapped to a spare speedtouch 585 but the same thing happened. I have tried accessing through another computer without success. All computers are using ethernet connections and one computer is on all the time uploading small amounts of data.
Anyone any ideas?
Mike

[#2]

Are you running any software firewalls?
If you are try turning it/them off and seeing if that helps.  If it does you'd need to look at the configuration of the firewall (is your router's home IP in the trusted zone for example?).
If you're running more than one firewall(including the Windows built-in firewall) make sure that you only re-enable one (you should only ever run one software firewall on a system).

[#3]

Just running windows xp firewall with kaspersky anti-virus - Same happens if I only use the PC running vista home edition with as it comes setup.
Mike