I've been having issues since installing Windows 7 Ultimate 64-bit copying large files to and from my hard drive, an external USB hard drive, and a network NAS. I made a few DVD ISO for archiving on my PC using ImgBurn and then trying to copy to my DNS-323 NAS or an external hard drive. When I copy large files (3+ GB), the source and destination checksum don't match. So I delete the new copy on the NAS and try again and then the destination has yet a different checksum still different from the source. I don't know if it my checksum program having issues or Windows 7. I have used both HashTab v3.0.0 and sha1deep (both free) without success. I also had trouble trying to copy a 6GB download from Direct2Drive. The only way I am able to consistently successfully copy the large files is to use a command windows and use xcopy. At first I thought it might be bad RAM but I ran memtest86 for approx. 18 hours or so and there were no reported errors. The NAS and the PC are connected via network cables (i.e. no wireless) through a 5 port DLink gigabit switch. My PC is a Core 2 Duo E8400 with 8GB of RAM and a 500 GB HDD. The NAS has dual 1.5 TB drives in a RAID 1 array and the external USB HDD is also a 1.5 TB drive. Has anyone else experience file copy problems with Windows 7?

Hi,Try to turn off Auto-tuning.1.press Ctrl+Shift+Enter to open the Command Prompt. Choose run as administrator.Type in: netsh int tcp set global autotuninglevel=disabled 2.Reboot If you have any problems, then to turn auto-tuning back on type the following in Command Prompt: Type in: netsh int tcp set global autotuninglevel=normal See if the issue is resolved. For references:Slow Large File Copy Issues Best RegardsDale

Dale, I realize this might be slightly off topic, but does this method of changing settings persist across reboots?Do not meddle in the affairs of dragons, for you are crunchy and good with ketchup!

Hi DemmyDemon,Based on my experience, slow large file copy issue can be related to Auto-tuning. Thus I recommend the OP to try. Totroubleshoot issues, we may need a couple of tests, don't we? Best RegardsDale

I found this: http://blogs.technet.com/askperf/archive/2007/05/08/slow-large-file-copy-issues.aspx#1723885 Which talks about disabling Remote Differential Compression and even though it is specifically talking about Vista and slow file copying, I tried it and I have successfully copied a file successfully from the NAS to my box with matching checksums. I of course will try a few more copies back and forth and see if I get consistent results. The auto-tuning also looks interesting and I will also re-enable Remote Differential Compression and try disabling auto-tune as well.

Sorry, first time using these forums, I guess I should have posted here have it show up at the bottom of the thread: I found this: http://blogs.technet.com/askperf/archive/2007/05/08/slow-large-file-copy-issues.aspx#1723885 Which talks about disabling Remote Differential Compression and even though it is specifically talking about Vista and slow file copying, I tried it and I have successfully copied a file successfully from the NAS to my box with matching checksums. I of course will try a few more copies back and forth and see if I get consistent results. The auto-tuning also looks interesting and I will also re-enable Remote Differential Compression and try disabling auto-tune as well.

Hi plisskin,What's the result? Please keepfollowing up to let us know. Thanks.Best RegardsDale

Well it was too good to be true. Copying some larger files still resulted in corruption. I did not get a chance to try disabling the auto-tune though because I found the issue: Bad RAM. Even though I ran memtest86 for a long time and had no errors reported, I still had a hunch about the memory. I removed (the newer) two sticks to drop back down to 4GB and have had no problems since. I've copied large files back and forth to the NAS and external HDD and downloaded the file from Direct2Drive again, every time getting a consistent (and correct) checksum on all of the files. I've re-enabled Remote Differential Compression and still had no problems. I was going to try swapping the RAM sticks in my PC to see if the problem comes back but laziness and a working system has so far stopped that plan. It is possible I suppose that the problem still could be with Windows 7 not handling that amount of memory properly (extremely unlikely) or a bad motherboard (possibly) but I am satisfied with 'only' having 4GB. I had only put in the extra two sticks because I happened to have them just sitting there. One other piece of information that was probably relevant was that my Firefox would sometimes crash unexplainably. I had thought this was a separate issue related to 64-bit and some of my extensions. Until IE8 crashed once in a while too. Then they would continue crashing more regularly until they rebooted. I think they were getting cached in the same location in memory and that would cause the continuous crashing until reboot. I've had no further browser crashes since removing the memory either. Thanks to everyone for there suggestions. Chris

I am having a similar problem. When copying files to an external drive, some become corrupted. Checking with sfv or md5 fails because of a checksum mismatch. The errors occur randomly and more often with larger files. Strange is that it happens frequently with one USB drive while the other in another USB enclosure has less problems. I also noticed that sometimes the calculated checksum was ok but after checking another time it was corrupt although I hadn't changed anything. Everything is pointing at the RAM in my view. I'm running an Intel P35 with 2 GB RAM.

I'm getting crazy here. Each time I calculate a checksum for the large file (4,36 gb) on the external usb drive it gives me a different value!! With internal drives it's working just fine. But I haven't had programs not working when copying files on the drive. Could it be that the binary information of the file itself is ok but Win7 stores some hidden metadata with a file that confuses checksum programs? How can I tell if the data is copied ok or not?

No solution to this one, right? That's a real bug that Microsoft has produced here! Big trouble.

I too, am having intermittant troubles with Windows 7 x86 on a Dell T3500 (Xeon, 4GHz RAM) I'm using md5sums in command line to decipher this issue... where a 100mb pdf copied from the main pc to another hdd or network drive fails checksums... The file was copied with a click and drag or with command line copy. i tried diff, comp, fc, to see what the differences were, but the output varies. the only fix i found for it was to use dd to copy them, then the checksums matched exactly. do note, this happens sometimes, and not all the times, and more with larger files..

wow. i didn't know this was over a year old... anyone experiencing my issues?