I used noobs_v1_3_2.zip installation and chose raspbian (according to the release notes date, it is the 25-09-2013)
I used su (and even tried sudo jtag) but the same jtag>detect error message appears
I used su (and even tried sudo jtag) but the same jtag>detect error message appears
Check what programs you have running in the background, also what modules are loaded at the time too...
Use ps wax to list active processes
Use lsmod to list loaded modules
Kill any unnecessary processes and use rmmod to disable any modules that are obviously unnecessary or which might be interfering with the GPIO pins.