The problem was the size of the shapefile. I ran the Dissolve tool over the week-end and it worked. It took 40 hours to complete the process. The first 1% shows up after 45 mins. I was no patient enough and though it was not working while actually I should have waited longer. Thanks

The problem was the size of the shapefile. I ran the Dissolve tool over the week-end and it worked. It took 40 hours to complete the process. The first 1% shows up after 45 mins. I was not patient enough and though it was not working while actually I should have waited longer. Thanks