I don't understand why "no problem" is such a bad response to "thank you." When the doctors I work for give me a task and say "thanks, Deb," I tell them "no problem" meaning that I'm glad to help - no bothers, no worries - feel free to ask again. But I usually say, "no problem - glad to do it" or something along those lines, and I say it with a smile and with some enthusiasm to make it clear that I mean it. They've always looked pleased with that response, or at least I've read it that way (and I still have a job after almost 15 years!).

Other languages have responses that, if taken literally, could sound different. In Spanish, "gracias" is replied with "de nada" which means "it was nothing." In German, "danke" is replied with "bitte" which is used for both "please" and "you're welcome."

Tone makes a lot more difference to me than what is actually said. Lots of people say "thaaaanks" or "pffffth - well, thanks" and it's obviously not sincere. I'll take a "no problem" over an obviously condescending "why, you're most certainly WELCOME" any day.