Me and my girlfriend were driving home and I noticed the abs light and traction lights came on. Also the radio went blank and A/C stopped blowing. Then the airbag light came on. We parked it and Tried starting it but it just clicked like the battery was dead. I removed the negative battery cable and let It sit for a while. We tested the battery and alternator and both were fine. I hooked the battery back up and it started just fine. We went to drive it again and it did the same thing except this time allthe lights came back on then everything went dead except the motor. The security/theft light started flashing like it does when the car is off. I'm wondering what the problem is and how to fix it.