Chevrolet: Serpentine Belt on 1995 Corsica, power stearing, serpentine belt

Question
About one week ago the serpentine belt on my car began to break/fall apart.  I had just replaced it 6 months earlier so I took it back into the store and they replaced it under the warranty (I installed the belt).  Everything seemed okay until 5-6 days after I installed the belt.  I heard the same sound of the belt beginning to fall apart.  The belt seems to to be falling off of the pulleys one rib at a time.  The belt didn't completely break off but one of the ribs would tear off all the way around the belt.  Some of my friends told me to check for a siezed bearing or a burr on a pully to see if that is causing some damage but I couldn't find anything wrong with the bearings or any burrs.  I also checked the alignment of the pulleys and they all seemed alligned.  I did notice that the pulley attached to the power stearing pump is a little loose.  It can slide along its axle about 1/8 of an inch in and out of the allignment with the rest of the pulleys.  Could this be causing the belt to gradually slide off of the pulleys and then rip the belt apart one rib at a time?  I looked up prices for power stearing pumps and they're not too expensive but I would like to know if it is difficult to replace something like that on a car for someone who enjoys working on cars but has little automotive experience.  Any advice as to what the problem would be or how difficult it is to replace the pump would be greatly appreciated.

Answer
Hi Corban;
       It seems  that there must be something cutting into the belt at some place or/ the adj,. arm is too tight and causing the belt to wear down fast. is the belt too tight ?
as far as the power ster. if you have all the tools  it should not be to hard .