|Quoted from this symantec KB:|
Safe mode is the Windows diagnostics mode. When you start the computer in Safe mode, only the specific components that are needed to run the operating system are loaded. Safe mode does not allow some functions, such as connection to the Internet. It also does not load all drivers for all software programs including drivers for some of the NAV program features, including Activity Log, Auto-Protect and Email Scanning. Because of that, these features do not function in Safe mode.
NOTE: You can run a manual virus scan in Safe mode. However, if NAV repairs a virus, the scan activity and virus repair results will not be added to the NAV Activity Log.