I am having problems with 4.0.314 on XP SP3 machines and having horrible response from Windows explorer when downloading files via FFox. Noticed that there was a newer build 424 so I downloaded the business version (since that is what these machines are running) and tried installing it on one computer over top of the 314 build. That was a big mistake. First got several messages that the account (admin) did not have rights to install. So I uninstalled it and rebooted and deleted the directory. NOD32 installs and seems to update ok. Then I reboot and it complains that it can not communicate with the kernal! So in otherwords the computer is sans antivirus! During the install I shutdown any software firewall. Quickly loosing confidence in NOD32 as the lockups are so severe at times that it is almost impossible to even shutdown systray applications let alone going to "Go to Protection status -> Statistics and check what file is being scanned by antivirus and antispyware protection.".