When my broadband connection connects to the internet it shuts my computer down everytime. I have run a Mcafee virus check which shows nothing and I have zone alarm firewall running. Any ideas how to prevent this or what is making it happen?

Is this a new problem? Were things woring OK previously?

Any new hardware and or software?

Try turning off Zone Alarm.

Also: look in your Event viewer: rt. click My Computer then click Manage then Event Viewer.
Or: Administrative Tools/Event Viewer or Start/Run/ eventvwr
Open the system as well as the application tabs & look for X errors. Click error line for details.
Post back the source & event id & Description especially of errors that seem to coincide with this issue.
Also check the Information lines that might coincide with this issue.

How to view and manage event logs in Event Viewer in Windows XP

Also view your Error Log via:
[1] Start Menu
[2] Help and Support
[3] Pick a Task
[4] Tools
[5] Advanced System Information
[6] View the Error Log