Moving files b/n 2 internal drives keeps hanging

Hi, I've been trying to move files between two SATA internal drives and it's going very slowly - about 30 MB/sec on average. In the Windows dialog box that you see while the files are being moved, I noticed that it hangs for 20-30 seconds, continues, hangs again, etc. which is really slowing it down.

Also I've noticed that in My Computer, the drive which the files are being copied to has no entry shown under the "total space" and "free space" sections while the transfer hangs. I just did a CHKDSK on the drive which the files are being copied to and it checked out fine.

Any ideas? This is on my desktop and my system specs are included in my profile. Also I've only experienced this over the past few days, up until now it's been fine with transfers over 100 MB/sec.

Thanks

 

Are the 2 Seagate 4 TB drives in RAID 1 ? If so, check the RAID.

 

No, no RAID, all individual drives. I'm copying files from the 3 TB Hitachi to the 4 TB Seagate.

Also just tried syncing the drives using ADCS (sync program) and was getting >150MB/sec, seems like it might be something with Windows?

Thanks