[Gmod-help] Player Model disapearing?

[hugom22 at aim.com]

Hi and thanks in advance for the help.  Ok, so whenever I get into a 
vehicle, any vehicle, my player model just disappears, so when i go 
into third person and look in the vehicle it looks like the car is 
driving itself.  This also happens when I try to use RT cameras.... Was 
it a download or is it some kind of an error, because my brother has 
this problem also.