Just to make sure the bases are covered, have you tried:
Different USB slot on laptop?
Download mode w/battery out?
Using a different computer?
Determined repeated attempts at rebooting computer, re-downloading and re-installing drivers, reattaching phone, etc., etc. until Odin recognizes the phone.........the way an insane person would do it?
Fascinate History: Stock, Stock Debloated with TB, SC3 w/ stock kernel, SC3 w/ Lean Kernel, SC3 w/ KGB, TSM Res w/ KGB, CM7 w/ Glitch V13.1, AOKP m4, b29, b30, Gummy 1.0, AOKP w/Glitch b32, b34, m5 DEVIOUS, b40 DEVIOUS, m6 DEVIOUS w/Devil, CM10 nightlies, BAKED JB