The RCEXL opto kill switch created a problem for me until it was removed.
On 12/2/2011 I posted my problem with the RCEXL opto kill switch in Post #139 on page 6 in the "Has anyone tried the new PTE36R ?" thread http://www.rcuniverse.com/forum/m_10..._6/key_/tm.htm
Preceding that post there were a number of posts in which people were trying to help.

Post #142 and Post #150 followed my post and may be of some interest.