Xbox 360 S reboots when I sign onto my Xbox Live Profile

Hmm, that's quite odd. Is the GT on your hard drive, or is it on the internal 4GB memory?

it's actually on a flash drive at the moment, it also did it on the 4gb and the HD. It stopped doing it after I formatted the hard drive. I'am now slowly downloading data again a little here and there until i get back up to the 70gb i had on it just incase i downloaded to much to fast and overheated the HD and maybe corrupted some data.

I dont think its a problem with the harddrive because I am having the exact same problem

2 different 250gig hard drives have 71gb's of data loaded onto them and I log onto the profile associated with them and it just keeps rebooting over and over.

Hmm, okay. Do you have another console you can try recovering your Gamertag to? Just to see if the same thing happens?

got a different console........put in the 250gb Hard drive logged on to my profile. Reboots, tried a different profile reboots. So at this point I'm left with the conclusion that the 1st Hard drive I had became defective somehow, got a new one now it is in the same state. Somehow I managed to get 2 hard drives that *** up only when the area of 70+gb's is loaded onto them. Mind you the 1st drive I basically loaded non-stop until it was done and the 2nd drive I took a week over small increments to load the same amount.  And yeah I've recovered the GT but since other GT's are now doing the same thing, so it has to be a bad hard drive.

Alright, What was the last thing you downloaded on your hard drive?

I got another hard drive and its working fine. I suggest trying to get another one, because since our problem is the same it's probably the hard drive's fault for you as well.