There are a few reasons why your report may show websites accessed when no one was actively browsing.
Temporary Internet Files and Cached Websites:
As you browse the internet, cookies and cached pages are stored in your browser window. Sometimes the browser will automatically update these files to keep them current and ready for any re-visit you make to the page (these items are designed to make pages re-load faster if you browse back to them). If this happens, the application may see this is a website being visited all over again, and add that site to the report. This is especially true of any website that was previously flagged by X3watch.
Incorrect Time Zone Settings in X3watch:
Another reason is that that time-stamp setting in X3watch is not correct for your time zone. To adjust this settings, log into your account (https://www.x3watch.com/users/sign_in) and click the "Profile" option in the navigation bar. Scroll down to TimeZone and ensure that this setting is correct (be sure to save any changes before leaving the page)
Malicious Software like Spyware, Malware or a Virus:
If you suddenly see an increase of website activity appearing on your reports when no one was at the computer, or of websites that you did not navigate to when browsing, it could be a malicious program that has been downloaded to the computer. It's a good idea to scan for viruses, spyware and other malware by using a trusted Antivirus and Anti-Spyware program.