Sounds like the same thing that happened to me. Pay careful attention where you place the antenna's when using 2.4. I put mine too close to the wing tube and I ended up with an unintended rolling circle 5 feet off the ground.
Take a look at this forum:
http://www.rcuniverse.com/forum/m_89...tm.htm#8952785
Following the advice of others I now have both antenna's in old push rod tube, one antenna pointed horizontally down the fuse and the other pointed vertically straight down. Haven't had another quirky problem with the radio. Hope this helps.