I'm stuck. A short while ago, I came out of an enclosed elevator into an area where there was a robot gun turret. I had earlier operated this to kill the half dozen guards standing nearby. It was the first turret I'd seen that fired a laser rather than bullets. Hopefully, that identifies the place I'm talking about.

Soon after, I come to a room where there's a waist-high pillar which I operate to all-too-temporarily switch off the electricity that injures you if you walk across it. I think that's what activated a force shield that prevents me from leaving the area. Then, there's another force shield, with a button to switch it off. Beyond that, there's another force shield, and the trick is to switch the damned thing off.

To the left is another room containing three workers and a button that produces an audio message of “Area Secured. Stand down from code red.” Killing the workers yields only a few credits. I used to refrain from killing workers because there are, like, INNOCENT PEOPLE. Then I found one with a keycard and others with medikits and stuff, so now I always kill 'em.

So I've interacted with everything. I went back to the waist-high pillar and operated it again, but that didn't help. I wonder if you have to do things in a certain order, but I think I've tried all the possibilities. With so few things to interact with, it really shouldn't be a problem, but, by Jiminy, it truly is.

Who can help?

I believe on the wall near the electrified floor, there is a tiny glowing red spot, that if you pass will reactivate the floor traps. If you draw your weapon and aim at it, you should see crosshairs targeting it. These are sensors that set off traps, so you should keep an eye out for these throughout the game and destroy every one that you see. That might be what's re-activating the force fields.

Your post was illuminating. I thought I'd interacted with everything, but I'd missed that thing on the wall. Sadly, the force shield is still up, so I still need help.

If there's anything that resembles a generator, try blowing it up as well. Other than that, I don't know how to get past the force field. =/ In the worst case, you can download the hint book here, which has all the maps and locations of every switch and trap:
http://www.pixsoriginadventures.co.uk/downloads/

In the room with the three workers is a large machine surrounded by 11 smaller ones. The large one is resistant to gunfire and spider bombs while the smaller ones blow up when shot a few times. I got them all to blow up, which used up all my ammo, but the forcefield that kept me in the room stayed on. I think the answer is in this room, somewhere, as I don't know what the button does.

Thanks for pointing me to the cluebook. I think I'm on mission 4, but I can't find the exact part.

It turns out I'm only on mission 1, which is great news, as I have much pleasure in store if I can only get past this problem. I thought my current mission - “Locate thermal coupler on level four and destroy objective with blastpac” - sounded like mission 4. I'm at the places shown at the bottom of page 73 and the middle of page 123 of the cluebook.

The dot location map in the cluebook told me that there are no objects I've missed. The events described in the walkthrough don't seem to match what I've been doing. There's nothing that resembles the bit where I took control of a gun turret and killed guards, and I certainly can't find my current situation.

I'm supposed to do something at the bottom corner of the room with the workers, but there's nothing there that can be manipulated.

Yeah, I remember getting stuck here, too. The big thing in the attached screenshot is the generator, the destruction of which is the goal of this whole mission. To destroy it, you need to use the thing circled in the screenshot. Just place it in front of the generator. He'll crouch down, place it, and then stand up. A few seconds later it will blow up, destroying the generator and almost everything else in the room. There should then be a cutscene. After that, the force shield will be open.

That works. Thank you very much indeed for saving me – again. I had wondered what the thing in the screenshot was.

Just got your message but it seems like Daedalus1138 already beat me to an answer ;)

Just so you know, there will be other missions where you'll have to find some computer/ terminal/generator something or other. If you use the datapad (the thing that looks like a black mobile phone turned on its side) in your inventory, it will show you a picture of your objective so you'll know what to look out for in future missions.

That's useful to know, thanks. It would have told me what I was supposed to be doing here, but since I didn't realize the blastpac was a blastpac, I'd still have needed help.

I have another problem brewing. This time around I'll remember to specify that it's a question so you can get some karma when you resolve it.