Thank you so much Tafoid,
I checked my default cfg file and it had L-Alt and mouse button 2 assigned.
I removed the mouse button 2 and Thrust now works as expected.
Wiliamo

In all Blasteriods versions, the thrust is not maintained. It just emits a quick burst then stops. Can anyone confirm this?
Asteroids works properly, so I know my controls are configured properly.
Thank You.