This game keeps tabbing out every 3 seconds

[Serpentry]

What is the cause?

[Bonus!]

probably a mod causing it if you have mods

[Bonus!]

or your system might be too powerful for the game to handle idk

[Wai]

May I just confirm, the game continues to run when you return to the desktop, or, are you crashing to desktop?

IF THE FORMER, the following might help:-

Verify your game files.
Re-plug the Keyboard.
Update Your Keyboard and Graphics Card Driver.
Run the Game in Windowed or Borderless Mode.
Run a Virus Scan.

No promises, but, worth a try.

(There is also the possibility that a background program is conflicting with Oblivion, if this is the case, or you think it might be try disabling those you can disable safely. Or, search the net for more detailed help. Also, it is possible a mod is responsible. Try disabling them all and then reintroduce slowly if your game works in vanilla,)

IF THE LATTER, try:-

Verify your game files? Right click on your game title in the library then select Properties, Installed Files, Verify. (Verifying can take a several minutes).

If verifying the files does not work, try this (it takes only a few minutes):-
Turn off Cloud storage if used.
Locate the Oblivion Documents folder.
Delete: BlendSettings, Oblivion and RendererInfo files from the Documents folder.
Start the game and save.
Exit.

(Note: The three files, BlendSettings, Oblivion and RendererInfo, auto regenerate if they are not found on start up, so deleting them can do no harm.)

You can now turn the cloud back on if you wish.
You will need to reset your screen resolution using the Option on the Launcher window.

This usually works for start up problems. No guarantee but is takes only minutes and it can do no harm.

(Note:- If you are using mods, it might be wise to disable them before trying any of the above and see if the problem persists in vanilla,)