Having worked 3 months for an ISP, I came across this a lot. There is often a clash between (e.g.) Zone Alarm & Outlook Express. Given precise details it is usually straightforward to resolve the conflict (without totally removing Zone Alarm). The easiest self-help option (as long as you can still log on to the net, or have a friend who can) is to note the content of any error message ('Print Screen' is good for this!) Then.. Google for the precise error message. Usually just the error code will be sufficient (e.g 0x800ccc0d). And follow the recommendations.

Nigel