I just replied in the other thread about the phone powering down before I saw yours...my phone started out with the send key not working and then I noticed that the 7,8 and 9 keys were not working. I took it in and they replaced it with not problems. I just remembered that I took my daughters phone in for the OK button not working...(she seems to have so many problems with phones I forgot) and they replaced hers as well.
Just remembered this also....first they wanted to update the phone with the V7 software because they thought that would fix the OK button....but it didn't. I brought the phone in 3 days later and they replaced it then.
My and my sons phone had V7 software this time so we didn't have to go through that.
I had an inside key (specifically, the right arrow on the navigation pad) that stopped working correctly. I had to press in the upper right corner--not on the actual arrow sign--for it to work. In-store tech support said it was not fixable. I took it apart to see if something like dirt was causing the malfunction. Air cleaning the inside and such did not fix it. Fortunately, right navigation still works just not well. I've learned to adjust to it (I don't have insurance and I'm thinking of getting rid of it anyway so I don't want to pay the $50 for a replacement).