World of uncertainities!!

ufff!! I'm fed up with this world of uncertainities. One evening when i was thinking of my uncertain future, my roommate( my best friend ) comes to me and disproves the Heisenberg's Uncertainity Principle. Then I thought...."damn! My next few seconds are so totally uncertain." He is so damn intelligent that nobody can even dare to argue with him (i can bet my ass on that, but sadly for him, i do dare to argue ;) ) I asked him to carry on with his explanation of the disproof. He went on.........

First he started with the principle. The principle is " locating a particle in a small region of space makes the momentum of the particle uncertain; and conversely, that measuring the momentum of a particle precisely makes the position uncertain."  Now starts the disproof.....

He asked me to consider 2 parallel beams in completely isolated conditions. Each beam consisting of particles called......(i'm not mentioning the name ;) ). They are just very small particles. And the distance between the two beams is supposed to be really really small and let it be dx (apt language i guess!!). Now consider an electron which is travelling along the perpendicular to these parallel lines. Let us have a latest technology computer which, at every nanosecond, shows us the position of the particle (it has to obviously be between these two parallel lines). Let us give a certain initial velocity 'v' to the electron, and zero accelaration. The time 't' it should take for the electron to reach the other beam from one beam is dx/v.

Everything fine till now. Now he says, let the electron travel for t/2 seconds. After t/2 seconds we can determine where exactly the electron is. Because after t/2 seconds the electron is at a distance of vt/2 from the beam it had started it's journey. 

Now this is exactly where the principle fails. At the instant t/2, the electron has a velocity of v and it's position is vt/2 from the first beam. So, at a particular instant we can determine both the position and the velocity of the electron. Yippeee!! First time, during the whole explanation, that something looked certain to me ;) . What he said was actually correct. As usual I started my own arguements. 

I'm not gonna tell you what my arguements were. Send in your arguements and let's see if you can disprove my friend.After all his explanations I went back to thinking about my uncertain future. Shit!! uncertainities again!! Boy, I really enjoyed those certainities in between.......