I'm having exactly the same problem with Sandisk Cruzer 64GB. Was formatted FAT32 and it was fine...since I needed to put 6GB SQL database archive on it, it had to be formatted NTFS. After format - Windows 7 (32bit) explorer was frozen, when I pulled USB stick out it un-froze. Insert it again - frozen. Only when I used ESET NOD32 Antivirus (32-bit) 7.0.302.26 "Temporary disable protection" everything was ok! Enabled protection again - again frozen on USB insert. I tried it on another computer without ESET AV - everything was also ok. So it is, no doubt, problem in ESET. P.S. "Device control" is unchecked/disabled...I tried all my other USB sticks, some FAT32, some NTFS (but smaller sizes, not 64GB if that matters...) and everything was also ok...it is just this Sandisc Cruzer 64GB (not faulty in any way) that when inserted frozes explorer until removed. Same on all usb ports...
