Driving along tonight in my 2006 E53 with Sirius and all of a sudden...poof....Sirius disappears.....the radio changed to CD instantly.....now I can not locate Sirius anymore.....just radio, aux and CD.....wtf?.....anyone experience this?....is the satellite unit next to my battery dead?

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Current BMW's:
2013 E70 X5 xDrive35i Premium (mine)
2014 F25 X3 xDrive28i (hers)
Past BMW's:
2001 E46 325i
2001 E46 330ci
2003 E39 525i
2006 E53 X5 3.0i
2008 E70 X5 3.0i
2014 E84 X1