I bought an i550 for a dive trip in March. when I got back from the trip, the only dive in the log was the last dive. Called Aqualung and they claimed it was the first they have heard of the issue (guess they don't monitor this forum). They suggested I connect it to my PC to see if I could pull the dive history out and take th computer back to my LDS for return to Aqualung. I connected the computer to my PC aand, sure enough, the data for all dives loaded to my PC.
So, I took it back to LDS, explained the situation and asked that they send if back to aqualung. They did a series of test dives over a couple of weeks and the dives did not disappear from the log. So, I picked it up and played around with it a little at home, including changing the gas settings. Set the computer aside for a couple of days. Turned it back on and all of the dives were gone. That is when I realized that the last dive I did on the original trip was after changing the gas type.
Took it back to the LDS and showed them the proof that their test dives were gone from the log. I explained my theory about changing the gas type. They agreed to send it back to Aqualung along with written details about changing the gas type.
Weeks passed. I just happened by the shop and went in to check on things. They had gotten the computer back from Aqualung, but Aqualung failed to return the boot that goes around the computer. They showed me some paperwork indicating that Aqualung had done a bunch of test dives and found no problems. There were a bunch of dives in the log. I told them to keep the computer until they got all of the parts back. I also changed the gas type before handing it back over to them.
Today, I was able to go back to the shop and pick everything up. The first thing I did was check the log and there were no dives. The LDS was good enough to replace the unit with a new one. I will find out as soon as I can if it has the same issues.
Two reasons for this lengthy post...One - can any other posters who have had this issue correlate it to changing the gas type? Two - If you are thinking about buy this computer, DON'T!