File Explorer keeps opening

We need a whole lot more information
What is the make and model# or your computer or motherboard? Tell us the specs on the computer.
Which version of Windows 10 are you running? Go to search and type Winver, tell us in the next post
How long has this been going on? Have you tried a System Restore to a time before this happened? Do you have an Image file of your computer?
What folder does Explorer open to? Is this only on Startup? or does it happen randomly? Have you gone to Task Manager and seen if there is any Task to start Explorer?

Sandi,

And is this set?

File explorer,
File menu,
Change folder & search options,
View tab,
Restore previous folder windows at log-in.

Denis

And if it's not what Try3 suggests:

History: (so very often omitted by posters)
- when did this start happening?
- what happened around this time - did you make changes- if so what?

Do you have a suitable System Restore point you could use?

When does this happen?
a. Repeatedly after you have logged in
b. Once only after you have logged in
c. Something else... what?