Front Derailleur Shifting & Turbo Problem

Lo [:p]

I have a problem with the front derailleur on a compact chainset when I shift up to the big ring on the bike upside down it shifts up ok but when I am on the turbo I have to turn down the limit screw a bit for it to shift up, when I try it upside down again the chain gos right off the chainring so I have to turn the screw up. I cant seem to get a good in between?

I have a Trax turbo cant remember the model number but it has settings 1-10 I can shift ok up to 3 then I have a shifting problem with the front derailleur that must be due to the resistance? but I didn't have this problem a few months ago.

Out of interest which setting on the turbo should I use? I find setting 4 to suit me not to easy not to hard, is it true that you should take the tyres down to 80psi from 120psi so you don't blow the tyres when on the turbo.

EDIT: I have fitted new Dura Ace 10SPD shifters to replace broken 105 10SPD shifters, the front derailleur is 105 dont think thats a issue tho but worth a mention.