In practice today I was hitting with one of my Head Pro Tour 280s and it felt very harsh. I tried another one and it was as smooth as silk. I did notice the one I picked up was last strung way back in May (with Wilson NXT 17). I have several racquets so sometimes they go quite awhile without fresh string. Do you guys think it might be the string or could it be something more serious with the frame? I have not dropped the frame. It's kept inside the house so it shouldn't be a freezing issue. These racquets are getting close to 10 years old. I quess the easy answer is to restring and see how it feels, but it was so bad that I'm wondering if the frame has somehow gone bad. Anyone else experience something like that? Does NXT get harsh when old?