This happens generally in UE5 and UE4. You do not need to uninstall and install stuff again. That will happen in future. On nvidia, overlay test mode creates this issue.
Please run attached reg, in your registry file. Problem will be solved.
Windows Registry Editor Version 5.00
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\Dwm]
"OverlayTestMode"=dword:00000005
mpo_disable.reg (252 Bytes)