aston.exe is a part of Aston Shell replacement. More information can be found here.

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Aston shell is a powerful and flexible shell replacement application.
Unlike many competing products, you do not have to have an expensive powerful computer to run Aston. Combining high speed and eye-candy it consumes less RAM, than default Windows shell and needs few processor resources. It is fast and stable, so you can save your computer's power for other tasks.

Aston fully replaces standard Windows Desktop and adds numerous new features: