Mains Water Supply Issue

Hi I work after from home 2 weeks at a time and recently started to turn off the water supply to my flat. But on the two that I have done it on my return from my trip when I turn the water back on I get nothing. Eventually I have to call a emergency plumber who is also mystified as why the water is no coming on. In the end he takes of the stop cock tap to see if this is jammed closed and finds that it is fine and refits it. then turn the water back on still nothing then after a while the water magically returns. this has happened no and becoming costly have to call a plumber each time. It is getting to the point that I am frighten to turn of the supply for any long period of time. Background information Property Flat within a building of 7 flats (Only 1 floor) Built 20 years ago. There is a water shut tap on the ground floor for all flats then a shut off when it enters my flat on the first floor (this is the one which I switch of) My hot water is by way of a combi boiler. Reading up on the internet there is a suggestion that turning off the water for any long period causes a airlock to develop when switched back on. How do I avoid this happening? I was thinking that the next time I go on a trip I could turn off the water supply using the stop tap on the ground floor instead of the one in my flat. Any advice would be welcomed Regard Des