Basically same problem with my Vyper Air. Purchased in August 2012 and worked fine until recently. Transmitter works at beginning of dive but about halfway, I will get a FAIL message. Sometimes I will get very high readings and sometimes it will work intermittently through the dive. Had the battery changed a few months ago so the batteries should be good. Brought it into the shop where I purchased it along with dive profiles downloaded from computer showing the problems. Was told that the transmitter is working (always works at beginning of dive), wear computer on same side as transmitter, don't dive with a strobe, make sure no one else has a transmitter....Aside from wearing my computer on the opposite side to my transmitter, none of these suggestions apply. No longer on warranty so not sure if worthwhile sending it away for repairs.