I've also just started playing BLPS and the trainer even freaked-out MS Security Essentials in Win 7 which is a first for me. I had to disable Real Time Scanning otherwise it was closing the trainer saying it was detecting severe Backdoor malware afoot.
MSE even ignored the Exceptions I created, so the only way around was shutting down R/T scanning. Ah, well, it's been quiet ever since.
I just got 10 Legendary (Orange) weapons at Moxxi's tonight using it. It's been working for me.
I always run the trainer and the game As Admin. If you mean the Slots at Moxxi's, I use the top group of rewards. I click Activate on the Trainer, then set the reward to the Orange Weapon in the top section of the drop-down menu, then click 'Set' and that's it. I always make sure the game is already running and the trainer has been activated before doing the settings.
I remember it wasn't working right at first because I was using the wrong group of rewards. But since then, it's given me the orange Legendarys every single time without a miss. I get the Orange at Moxxi's and Purple from the Chest.
Maybe reset everything and try again in different orders. Like Press F1 at the main menu or if that doesn't work, try pressing F1 after joining the game. If it's still not working you may have to disable or uninstall your anti-virus. I had to disable my Real Time Scanning.
Yeah Ive tried a few different sequences of setting and activating. the moxxis slots do the same thing when activated everytime, it will stroke, then freeze up, as in never reset the slot machine or give me any weapon. when i deactivate the jackpot editor, it will usually unfreeze and give me a green weapon and then reset.