Follow these steps to ensure that the Windows XP Firewall is not causing issues with ACT!.

1. Launch Windows Explorer (or My Computer).
2. Right-click the My Network Places icon, and then click Properties from the shortcut menu. The Network Connection panel appears.
3. Right-click the Local Area Connection icon, and then click Properties from the shortcut menu. The Local Area Connection Properties dialog box appears.
   
   
   
   
   
4. Under the Advanced tab in the Windows Firewall section, click Settings. The Windows Firewall dialog box appears.
   
   
   
   
   
   
5. Under the General tab, enable the Off (not recommended) option.
6. Click OK to close the Windows Firewall dialog box. The Local Area Connection Properties dialog box reappears.
7. Click OK to close the Local Area Connection Properties dialog box, and then close Local Area Connection Panel.
8. Test ACT!.

For more information on how to create an exception for ACT! in Windows XP Firewall, please refer to the following Knowledge Base Answer:

Title: How to Add ACT! to the Exception List for Windows XP Internet Connection Firewall