Replying "you are welcome" feels like an acknowledgement that something I did to be a great deal, and to a Chinese (brought up in Chinese culture), this is embarrassing -- not I think it is embarrassing but I always automatically feel embarrassing. So each time even though I know I should reply "you are welcome", I always glitch out and when it come out, it is nearly always "no problem". Of course it means "no problem" for me (to do it or do it again), not that there wasn't problem for you that need help with. To a Chinese, attitude comes first and I have the first need of being modest (not as a virtue, but to actually feel comfortable). On the other hand, in Chinese culture, right or wrong is often not that important, so it is ridiculous that people would actually interpret "no problem" as a denial of their saying thank you in the first place (from the fellow comment, and this is actually the first time for me to understand why would some one give me over reaction when I reply no problem).
I actually always feel embarrassed (for another reason) when I realized I didn't say "you are welcome" and meeting some surprised expressions.
This article got me thinking and I decided that I should not feel embarrassed any more. There is nothing wrong in Chinese culture and I have been spent great effort coping with western culture half of my life and I believe most people do respect cultures. I will reply "no problem" and if people feel surprised I'll explain that is merely a culture difference.