HELP!!! Security problem

[j3ni_bee]

I just replaced the battery in my 2005 GMC Yukon Denali. After putting in the new battery the car will start but the parking and headlights are flashing. They flash for about 30 seconds, stop for 2-3 seconds then flash again and repeat this cycle repeatedly until the car turns off. I am able to drive the car around and have no other problems but these lights flashing. It happens every other time I turn the car on and the security light is also flashing. It flashes about 5 times then stops then starts again. I am stumped as to what to do. We have pulled the battery, disconnected the ground and put it back on, done the 10 minute and 30 minute relearn cycles for the passlock. Any other ideas would be great. Thanks in advance.

[j3ni_bee]

Anyone????? I guess no one else has had this issue.