my mac keeps periodically crashing too (kernel panic) after i installed the mac ant agent. might be a garmin or an apple bug. whichever it is, it might be a good idea to wait a little until potential problems have been ironed out....
also, automatic uploading to garmin connect did not work. when i tried to upload manually via the 'Upload' button on the garmin connect website, the browser plugin offers as datasources mounted removable devices as a SDHC card from my camera and a data volume mounted from my NAS but not my forerunner 405...
it worked loading the data into GTC, which is most important. i don't want to spend more time on investigating what went wrong with the garmin connect uploads as long as the kernel panic issue persists though.