It appears that my screen saver has not been enabled. If I am away from my desk for an extended period the screen saver is not activated.

How to customize Screensaver in Windows 10
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There were times when computer monitors used to suffer from image burn-in issues caused by showing the same image for a long period of time and people used to install a screen saver to avoid the issue. The computer screens today no longer face the burn-in issues, but people still use the screen saver on their computer systems for fun's sake. Windows 10 comes with a six built-in screensavers. Let us see how you can customize screensavers in Windows 10.
Read: Are Screensavers necessary and still needed.
Screensaver Settings in Windows 10 You can get to your screen saver settings directly by typing 'Screen Saver' in the taskbar search box in the lower left corner of your system. Click on 'Change Screen Saver' and it will take you the Screen Saver settings right away where you can adjust the settings according to your own preferences.
Alternatively, right-click on your Windows 10 desktop, and select Personalize to open Personalization settings. Next click on Lock screen in the left pane.

Scroll down the Lock Screen settings and click on Screen Saver Settings. The following window will open. Here you can adjust the settings according to your preferences.

By default, Windows 10 offers the following six screensavers - 3D Text, Blank, Bubbles, Mystify, Photos and Ribbons - nothing new here. Select the screensaver from the drop-down menu and change its defaults Settings, if any are available.
For instance, the 3D Text screensaver lets you customize the text as well as a few other options.

The Photos screensaver lets you display your favorite photos as a screen saver.

Once you are done, click on save and exit.

Create Screen Saver Settings Shortcut

If you access the screensaver settings frequently, you can create its desktop shortcut as follows: However, it is easy to change the settings but if you change your screen saver often, it would be better to create a Screen Saver Settings shortcut on your desktop.
To create the shortcut, you have to right-click on your desktop and click on New > Shortcut.
Type control desk.cpl,,@screensaver in the location space in the wizard.
Click Next and give a name to your shortcut. Click Next and you are done. Give it a suitable icon of your choice.
Use this shortcut to change or adjust your screen saver settings whenever you want, quickly.
You can also create a shortcut to launch or change Screensaver state for a specific screensaver.

hi

right click your desk top and select personalize


on the appearance and personalization page


at the bottom right corner is the screen saver click on it


screen saver drop down menu change it to none and press ok

cheers

What you are experiencing isn't "sleep" mode, it is the screen saver. If you have WINXP, right click on a clear area of the desktop, and select "Properties". When the DISPLAY PROPERTIES window appears, select the "screen saver" tab. Change the "WAIT" time to the time you wish the scrren saver to delay. If you don't want to have to login after a screen time out, uncheck the "On resume, display Welcome Screen" box.

The Energy Saver Mode deactivates the display to reduce energy
consumption.
To Activate the Energy Saver Mode:
1. Press and hold OPTIONS for 3 seconds. "Energy saver on."
will appear in the upper text area.
2. The setting will be activated after 5 minutes.
Any cooking function may be used with the range in Energy
Saver Mode by simply selecting the desired function.
To Deactivate the Energy Saver Mode:
1. Press and hold OPTIONS for 3 seconds. "Energy saver off."
will appear in the upper text area.
2. The clock will reappear in the display, and the range can be
operated as usua

Great presentation of your problem.
One thing I would check is the screen saver. You say as long as you use the computer it looks normal. Look at your screen saver settings to see if the lined appearing coincide with the screen saver time.
With computer parts, failure on a periodic basis (based on time) usually indicated a heat problem. This does not appear to be the problem in your case, as you say you can use the computer for an extended period without a problem. This is why I was suggesting a screen saver problem. You might even try a different screen saver just to test this. Possibly the part of windows that controls the screen saver (and don't ask me where that is, 'cause I haven't a clue) is corrupt.

Good luck.

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that could be the indicator for "you have voicemail messages waiting" -- It looks like a little tape cassette. Pick up your voicemail and it will go away.

as for the time display on the front screen, check that you have the screen saver enabled - Settings, Mini Display, Screen Saver, Digital Clock (or analog clock if you prefer), then check again to make sure it is set to On.

Screen savers can help protect your monitor from wear by showing a constantly changing display when your computer is not being used. Screen savers can be simple, like the Blank screen saver that turns off your monitor to save energy. To change your screen saver 1. Right-click your desktop, and then click Properties.
2. In the Display Properties dialog box, click the Screen Saver tab.
3. Click the Screen saver drop-down box, and then click a screen saver.
4. Click the Preview button to see how the screen saver will appear on your monitor.
5. Move your mouse or press a key to return to the Display Properties dialog box. To try a different screen saver, return to step 3. 6. Click the Settings button to change the standard behavior of the screen saver you selected. (Each screen saver has its own settings dialog box.) Then, click OK.
7. In the Wait box, type the number of minutes the computer should wait to start the screen saver after you last touched the keyboard or mouse.
8. If you are the only person who uses your computer and you are not concerned about security, clear the On resume, display Welcome screen check box. Otherwise, leave this check box selected. Note: If your computer is joined to an Active Directory, the Fast Users Switching feature will be disabled. This is a common change made to computers used for business, and it happens automatically when a computer joins an Active Directory domain. However, disabling the Fast User Switching feature is not the default setting. Almost all computers in home environments will have Fast User Switching enabled. When Fast User Switching is enabled, you'll see the On resume, display Welcome screen check box. If you're part of a domain, you'll see the On resume, password protect check box.
9. Click OK.

Screen saver mode, as you know, is entered when the computer senses no activity (including mouse) for a defined period of time. for some reason, the computer thinks there's been some kind of activity. If you have an extreamly sensitive mouse, vibrations could be being picked up "tricking" the computer into thinking there is activity.

The other possibility is that the computer might not be able to respond to the mouse if it went into screen saver mode (perhaps a preference setting with the wireless mouse) and has decided that while operating using a wireless mouse screen saver will be deactivated. Look into your preferences or settings relating to the wireless mouse.