Who’s been using your PC? Tell-tale signs that someone’s been using your computer

Think someone’s been at your computer while you’ve been away? Whether it’s a hacker or a hot-desking colleague, here’s how to find out what they were doing.

Sticking a ‘keep off’ sign on your computer is one way to stop other people from using it, but if you suspect someone else has been poking around without your permission, how can you prove it?

The easiest option is to look at the Windows Event Viewer - a built-in program that logs what your PC has been up to. If it’s been switched off or just sitting idle, there won’t be that much to see, but if someone else has been using it, you’ll see the tell-tale footprints they’ve behind.

[Read more: How to find your Android smartphone if it's lost]

View Windows events

Event Viewer

Open Event Viewer by typing event viewer into the Start menu and selecting Event Viewer from the list of results.

When the program opens, double-click the Windows Logs entry in the left of its window, then select the System entry. Then right-click System (you must select it first, else this won’t work) and select Filter Current Log from the menu that appears.

Event Viewer

When the dialog box opens, open the Event sources drop-down list and scroll down to find Power-Troubleshooter. Tick the box for this option and click the OK button.

Event Viewer

The main window will then show the times at which your PC has been switched on or woken from sleep. If any of these don’t match the times you know you were using your PC, then something is amiss.

[Read more: How to check your online web browser history and more]

Check for recently used files

Event Viewer won’t show you what your PC was being used for, but a little detective work might give you some clues.

First, open any applications you use often and check the Open recent (or similar) option in the File menu. Not all applications have this, but this that do will show you which files were opened most recently - look for any you don’t recognise.

Recently used files

You can also search for files that were modified on the dates you’ve identified. Open a window and type a related word in the left of the window, then select the Date modified option and select a date on the calendar that appears.

Recently used files

Windows will then search for all files in your Library folders that were changed in some way on that date. You can do the same thing for your entire C: drive, but Windows changes so many files in normal use that it will be impossible to make much sense of the results.

Check your web browser history

Web browser history

Finally, don’t forget to check your web browser history. This shows a list of all web pages that were opened recently and you can browse by date. See our comprehensive guide on viewing your browser history for more on how to do this for the most popular web browsers — but don’t forget that the browser history can also be cleared easily.

Don’t forget your password

Keyboard with Pasword Security on yellow key

Prevention is better than cure when it comes to keeping other people off your PC, so if it is a problem, for you, set a password on your Windows user account. Then, whenever you’re away from your PC, but don’t want to shut it down, just press Windows and L together to lock the screen. Click here for some tips on making a strong but simple to remember password.

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