I installed the xitel hardware/software package

I installed the xitel hardware/software package connecting it to my stereo and my Sony Vaio laptop. The installation went smoothly and when I tried to transfer a vinyl LP, the Xitel system appeared to work as advertised. But in checking the resulting files, I found that each track had been elongated by about a minute or so. On playback the difference between the original and the digitized copy was subtle - no pitch distortion - just a very, very slightly slowed tempo. Interestingly, the amount of time added bore no proportional relationship to the length of the track; the shortest of the 3 tracks I transferred had more time added than the other two which were about 3 times longer. Surfing the web I found no reference to this problem. Most of the LPs I am trying to transfer are classical music, chosen for qualities of the interpretation and a re-recording process that tinkers with that is not really satisfactory. Any thoughts?