Ok so this svcks, not sure if anyone else has had this happen. Im all but sure tho. I caught the spy went back to Hsu, then deactivated the bomb. (I tried bothways) and the outcome is the same, the Monorail blows up. A very annoying bug to say the least. Anyone else experiance this? I am just telling myself that there must have been another sabator that the NCR had no knowledge of and moving on. LOL But I am finding alot of bugs in this game wow.

You can't report to Hsu first. You have to listen to the spy, then go straight to the monorail and deactivate the bomb once the quest updates on your pip boy and THEN report to Hsu. Otherwise the game glitches and says you deactivated it but you didn't. Very irritating I know. I posted something to this effect before.

Yup, a patch better fix this.

This one was really frustrating. After many unsuccessful runs trying Agility help, etc., I finally used a Turbo to get to the door of the car but it wouldn't open. I got there, but it wouldn't open. I thought the whole thing was glitched and never did the alternate attempt of bypassing Hsu. So it blew up. The NCR sure are complaining but I figured they could save some money.

I had to visit Mick and Ralph's for a pass to get into the Strip.

Yeah, I was able to disarm the bomb, only to have it blow up anyway. Tried it several times. Finally I just hid and listened to the spy, then went and disarmed the bomb, which was successful.

It was odd, though, to see it say you had disarmed the bomb. I was able to try both ways, since I had pickpocketed the code from the spy. But disarming with explosives skill or the code, both would say that I disarmed the bomb, only to have it explode anyway.

But just listening to the spy, then going to disarm directly did the trick.

This quest was completely bugged for me. (I used wiki to help me try out different variations on the quest to try to finish it). Listening to the radio conversation was bugged - he only got one word out then went into caution mode, even if I was using a stealthboy. So that never progressed the quest. I could then confront him, kill him, and report to Hsu. This part worked, as I then had the update to go defuse the bomb. Had to use Turbo to reach the bomb (half of the loads I couldn't get onto the train as door was 'closed'), and even when I disarmed it the train blew up anyway.

Really frustrating but in the end I just went with it. Everything (plot wise) can't be perfect, and the NCR will just have to live with a broken monorail. If my character was 100% pro-NCR it would be more annoying.