I had similar elbow problems on both sides in the last few weeks. I suspected my MS Natural Keyboard to be the cause. Form and size of the keyboard fit my needs perfectly, but the keys are so shaky and sometimes get stuck, especially the control keys, it is just crap! So last week I changed back to my old non-ergonomic Cherry keyboard with micro switches and my elbows are getting better every day. I wonder if there is an ergonomic keyboard with good keys on the market.