Hi,
Here's some steps you might want to try with that PC.
Load into safe mode with networking and see if the same problem happens in there.
1. Turn the PC off completely.
2. Hold down the F8 button then turn the PC on while still holding down F8 you can let go once you see Advanced Boot Options
3. Select Safe mode with Networking using the arrow keys on your keyboard then press enter once selected.
4. Once in Safe Mode with Networking see if the same problem exist. If not
5. Perform System Restore to an earlier date an time when everything was working fine.
6. Lastly if it still is happening in Safe Mode you need to perform a Factory Reset. Use this link below for the procedure on how to do this.
https/www.dell.com/support/article/us/en/04/SLN117599/EN