I'm not sure why "use computer" wasn't working before - if you send me your ASL file I can take a look into it for you. Just email it to me at
[email protected].
The script commands in the Objects category "Make an object inaccessible" or "Hide an object" will do what you want with your "computer used" object. Perhaps an easier way might be to set a numeric variable to 1 when you have used the computer. Quest 3.5 will introduce an even easier way to do this, as you will be able to set a "flag" to indicate things that have happened in your game. I will be releasing a beta version of Quest 3.5 soon, but until then using a numeric variable might be a more elegant solution than using another object - but it's up to you, as always in Quest there is more than one way of doing things.