Acrobat 8 professional

hi i have acrobat 8 professional through creative suite3 it has worked perfect for the past 2 years but for the last 3-4 months when i try to create a pdf from word or excel acrobat goes through the motions but at the end acrobat opens up but nothing created. I have done numerous reinstalling creative suite or using adobe detect repair and it works for a few days then goes back to the above problem, my system is xp proffesional and office 2003 has anybody else had or heard of this problem that can help. Many thanks in advance