Using the current version of Mirc on Windows 11. When using the Alt + Tab key MIRC remains in the foreground and will not switch to the other applications that is running. I do not think Windows is causing the issue since all the other applications I am using works fine.

I tried deleting the config file did no fix the issue. I do know that error's in the code or using certain type of extra lib files could cause some issues.

Sounds like you have set mIRC to be "on top".

Click on the main mIRC icon in the top left corner and see in the "On top" option is enabled, if so click on it to disable it, see if that were your problem.

If on top setting is not your issue, which windows are you talking about/trying to alt tab to, are those mIRC windows or different programs like chrome notepad etc?

Can you confirm that you've not set mirc itself as 'on top'? The menu on the mirc logo in the upperleft corner has a menu choice for 'on top'. Or you can manually disable: /showmirc -p

By default when Mirc is installed is that normal and you have to type /showmirc -p and if so it should not be that way.

This feature is not enabled by default in a new install. Note that it can also be enabled/disabled through the "View" menu in the menubar by selecting "On Top".