I love the 600ex flashes and don't think I will go back to using pocket wizards, however I have one major complaint about them and I was curious if anyone else had the same problem. I have three of them that I use at wedding receptions. One on the camera and two slaves on stands. I always have the slaves set to manual at a low power (usually 1/32 or 1/64). I started to notice that some of the slaves stopped working and I just figured the batteries were out. I got battery packs hoping that they would last all reception which they should because my 580exII flashes lasted all reception with no battery packs. Well even the 600ex flashes with battery packs stopped working at really bad times which is annoying because if you have them all linked and one stops working then they all stop firing. I hate that so much and I don't know why it works that way. Last night I noticed the back of the flash that stopped working the whole display was a a reddish orange. Anyone know what that means? I turned the flash off and turned it back on and it worked perfectly the rest of the reception. Then the other slave flash did the same thing and again I turned it off and back on and it worked perfectly the remainder of the time. I just don't understand what is going on. I am using them at a very low power level it isn't like I am rapid fire shooting at full power. These wonderful flashes seem to have a serious problem.