7D + 50mm 1.4 : many misfocused shots

Hi,

After reading this forum for about a year, I registered because I'm puzzled with a problem with my 7D.

I grabbed a 7D 5 days ago and sticked a Canon 50mm f/1.4 for some tests. One third of my shots with center focus point where slighly blurry and all my shots with other/multiple focus points where completly misfocused.

I went back to the shop with my camera and lens and the salesman immediadly refunded me. We tested another 7d with another 50mm f/1.4 with the same result.

Has anybody else tested this combination ? Do you get sharp shots every time ?