We have a Agilent 34405A which sometimes gets corrupted, when it is switched on. In that case it isn't recognized in MAX (version 4.6 as delivired by the VISA 4.5 package running on a PC with Windows XP SP3 ) any more anf if you look into windows device manager, the USBTMC driver grabs it , but the device return a hosed serial number (the driver details view shows something like USB\VID_0597&PID_0618\7&348C4261&0&1 instead of USB\VID_0597&PID_0618\TW481150081). Usually that corruption is fixed when powercycling the 34405A .
Yesterday however we switched on the DMM and when booting the PC it crashed before the login windowshowed up. After unplugging the 34505A and rebooting we were able to login again. Then we removed the entry for it in device manager for it ( using the option to show unconnected devices ) and forced a reinstalltion of the driver after plugging in the 34405A again .That reinstallation wasn't successful. It started, but never came to an end. A hard reboot also ended with a crashed system until we unplugged the device again. Finally after powercycling the 34505Athe problem went away. So it seems that a hosed USB device can crash the USBTMC driver and Windows with it.
