Hi, I searched the internet high and far and have found many formatting issue posts all around but none that covers this particular error. I have a USB Stick with the following specs according to Disk Utility: Name : Udisk Udisk 2.0 Media Type : Disk Partition Map Scheme : Unformatted Disk Identifier : disk1 Media Name : Udisk Udisk 2.0 Media Media Type : Generic Connection Bus : USB USB Serial Number : 0001CFCFCFC5DB1C Device Tree : IODeviceTree:/PCI0/EHC1@1D,7 Writable : Yes Ejectable : Yes Location : External Total Capacity : 2.07 GB (2,066,743,296 Bytes) Disk Number : 1 Partition Number : 0 S.M.A.R.T. Status : Not Supported I can format the stick just fine in Windows but every time I try to erase the Stick or use the partition menu in Disk Utility it starts trying to "Unmount" the device until it times out with the following error: 2011-08-29 19:39:26 +0200: Preparing to erase : “Untitled” 2011-08-29 19:39:26 +0200: Partition Scheme: GUID Partition Table 2011-08-29 19:39:26 +0200: 1 volume will be created 2011-08-29 19:39:26 +0200: Name : “Untitled” 2011-08-29 19:39:26 +0200: Size : 2.07 GB 2011-08-29 19:39:26 +0200: File system : Mac OS Extended (Journaled) 2011-08-29 19:39:26 +0200: Unmounting disk 2011-08-29 19:42:01 +0200: Disk Erase failed with the error: Wiping volume data to prevent future accidental probing failed. 2011-08-29 19:42:01 +0200: Erase complete. 2011-08-29 19:42:01 +0200: After that the stick becomes unreadable and when plugged in again you get prompted that the stick cannot be read and OSX gives you the option to "Initialize..." which ends in Disk Utility again getting stuck on the "Unmounting" of the device. I even tried from the terminal with "diskutil partitiondisk disk1 JHFS+ newdisk 100%" without success, aside from the fact that I was able to get this error number: "Error: -69825: Wiping volume data to prevent future accidental probing failed" On top of the USB Stick listing in Disk Utility, it also lists a greyed out CDROM Icon Entry for the stick "Udisk Udisk 2.0 Media", can't do anything with that. I tried formatting this stick in all ways I can think of on a MAC under OSX and it just does not work. Why? Thanks for any input! Cheers, A.