I bought a Cobra Tag earlier this year after losing my phone at office. It has become a must of my phone but Cobra Tag started to crash this afternoon, after I upgraded my phone to Android 4 via HTC update wizard. I was going to contact Cobra for customer support, but soon discovered the root cause on my own before hitting the Send button.
The cause is rather simple: I was using a custom alarm tone (Microsoft Bing tone if you ask, as it is so unique), and that was broken after the firmware upgrade. After setting it correctly, and also re-pair the tag to my phone this issue disappears. I found it out, simply because upgrading the phone, I noticed that the Music app also experiences some issue re-scanning all my collection on the phone.
Therefore, a few minutes ago I modified the mail from an inquiry to a bug report. Hope Cobra developers can fix this issue after receiving my report, as the app should simply report it cannot find the tone music file, instead of quietly die.
[Update: Cobra recently provided an updated Tag app in Google Play which resolved all the issues. Excellent!]