I've had this problem with in-ear earphones for the past couple of years. No matter what brand or model I buy, I can't seem to stop them from not working in one ear a few months after I buy them.
I mainly use them to listen to podcasts and occasionally music, on a 4th Gen ipod touch. I wear them in the office, and have a habbit of getting it caught on things like side of the desk, or dropping the ipod etc. The last two I bought were Sennheiser CX 200 Street II (lasted about 2 months) and Creative EP-630 (lasted 3 months). Seems that whichever make I get, this keeps happening and I was wondering if this happens to anyone else, or am I just not that careful with them? Anyone got any tips for making them last a bit longer?