Are you sure it's the keyboard causing this? It sounds to me like it might be something specific to either an application or maybe an OS setting.
If it happens in every application (including Notepad, Word, your Web browsers, etc.) you might try the keyboard with a different computer just to see if you get the same results. If not, it might be some setting in Windows causing this. If it happens on some other computer too, then maybe there is some issue with the keyboard, but that seems unusual to me.
If it only happens in one application, it's probably a setting in the app itself.