Can you please provide the following information;
What is the computer’s operating system ?
What is the type of internet connection (cable/wireless/dial up) ?
What is the version of your internet explorer ?
1-Windows XP profecional Version 2002 Service pack 3
3-Mozilla Firefox 3.5.8
Please follow the below prompts, and try installing again
1. Start > All Programs > Mozilla Firefox > Mozilla Firefox (Safe Mode)
2. A window appears with few checkboxes:
Disable All add-ons
Reset toolbars and controls
Reset bookmarks to Firefox defaults
Reset all user preferences to Firefox defaults
Restore default search engines
You can reset or restore rest of things too.
3. Select the highlighted one Click on Make Changes and Restart
4. Run Mcpreinstall tool from http://download.mcafee.com/products/licensed/cust_support_patches/McPreInstall.e xe and try installing again.
Did you try installing with Internet explorer, if not tyr with IE and let me if you come across any issues.