When I try to log off i get error "no disk in drive x:/ with X being a particular drive"

Try removing any external device connected to the computer and check. Follow these methods:
Method 1:Follow these steps:
Step 1: Boot the computer in Safe mode and check if the issue persists. Follow these steps to start the computer in safe mode. a) Press the ‘Windows + C’ key on the keyboard.
b) Click on settings, more pc settings and then general.
c) Scroll down to advanced startup, click restart now.
d) Click on troubleshoot, advanced options, Windows Startup Settings.
e) Click restart, select safe mode with networking and then press enter.
Note: Restart the computer to start in normal mode.

Step 2:
If the issue does not persists in safe mode then perform a clean boot to check if any third party application is causing the issue, as clean boot helps in eliminating software conflicts.
Follow these steps to start the computer in clean boot.
a) Press the ‘Windows + R’ key on the keyboard.
b) In the ‘Run’ window type ’MSCONFIG’ and click ‘Ok’.
c) Click the ‘Boot’ tab and uncheck ‘Safe Boot’ option.
d) On the General tab, click to select the option ‘Selective startup’, and then click to clear the option Load startup items check box.
e) On the ‘Services tab’, click to select the ‘Hide all Microsoft services’ check box, and then click Disable all.
f) Click OK, and then click Restart.
Note: After performing the troubleshooting steps in clean boot, follow these steps to return the computer to Normal startup mode. a) Press the ‘Windows + R’ key on the keyboard.
b) In the ‘Run’ windows type ’MSCONFIG’ and click ‘Ok’.
c) On the General tab, click the Normal Startup option, and then click OK.
d) When you are prompted to restart the computer, click Restart.

Method 2:
Follow these steps:
1) From the Metro "Start" page type "Shutdown Settings" 2) Click the "Settings" Icon on the right of the screen.
3) Click "Change what the power buttons do" on the left of the screen.
4) Click "Change settings that are not currently available"
5) Scroll to bottom of Dialog box.
6) Uncheck the box titled "Turn on fast startup (recommended)."
7) Click "Save Changes" button.
8) Exit Power Options Dialog box.

Method 3:
If the issue persists in clean boot then, restore the computer to a previous state when it was working fine using system restore and check if that helps.
a) Move the mouse to the bottom left of the screen and right-click to get see a list of options.
b) Click on ‘Run’ and type ‘rstrui’. Click ‘OK’ to bring the ‘System Restore’ interface.
c) Following the steps as mentioned in the interface to restore the computer to a previous point.

Note: When you perform System Restore to restore the computer to previous state, programs and updates you installed are removed.