Yes, they can. Please see below for some instructions for disabling them for activation.

WINDOWS XP INTERNET CONNECTION FIREWALL:

1. Go to start -> Control Panel
2. Open Network Connections.
3. Right Click on the connection you use to connect to the network
4. Choose Properties
5. Go to the Advanced Tab
6.If your firewall is Enabled, turn if off for activation.

ZONE ALARM:
Simple instructions:

If you have Zone Alarm installed and try to run VisionWorks activation, Zone Alarm may pop up an item saying "Do you want to access the internet?"

Choose Yes. There is an option to allow this program to always access the internet.

Advanced instructions:

If you have been using Zone Alarm for a while and have not been able to get VisionWorks activation to connect to the internet, you may need to change some settings within Zone Alarm:

1. Start Zone Alarm Control Centre
2. Go to Program Control tab
3. Choose the Programs Tab
4. Make sure that VisionBackup.exe row has either checks or question marks in the access and server columns. If there is a red cross in these columns, click on the box and choose "Ask". Choosing "Allow" will also work.

OTHER FIREWALLS:

Please allow both TCP and UDP connections for optimal performance