I just opened a support ticket with Line 6 about this problem.
My Line 6 Spider Jam reboots when I try to access the SD-Card or do anything such as format the SD-Card.
It did work for 2 years and then this problem just started. I am hoping I can take it to Guitar Center (Where I bought it) and have it repaired.
I believe I did buy the 3 year warranty from them when I bought the amp.