fkeel:
so what happens if they all connect to a common ground, but you power the pushbotton and the sensor individually? i.e. connect the temperature sensor to a digital pin for +5v?If you have the bushbotton and the temp. sensor in parallel they are bound to interact somehow... (but that's just my intuition - I had a problem similar to that at some point and since then try to power sensors individually cause I now it will work that way. If I don't do it, I always have that slight uncertainty that something might be interacting...)
This results in the sensor returning between 0.5V and 0.6V more than it should