1998 Renault Scenic driveshaft

Steering problem
1998 Renault Scenic 4 cyl Two Wheel Drive Manual

i have owned my megane scenic since 2007. On april 7th 2009 it went for its MOT test and needed 2 bottom ball joints and a new offside suspension spring. I have been assured I bought the right ball joints, as there is only 1 size for a 1998 1.6e. On sunday 7th june I suddenly started getting a kncking and banging when steering left to right when the engine is in gear. I finaly got it to the garage today ( they was fully booked ) The mechanic called me back after he had got it on the ramps and explaind that he was baffled to why the OFFSIDE drive shaft should suddenly start coming out of the bearing connected to the engine side. He said he had had the problem arise b4 and had to fit a bigger drive shaft. But he was baffled why the original should start to come out now when nothing as been done to the drive shaft, just the new OFFSIDE suspension spring and the new bottom ball joints. Can any 1 explain this and what can b done? As any 1 had the same problem?