my system (winxp SP2) has 3 harddrives: - WD5000aaks-00yga - wd2500ks-oomjbo - st3250620as all are SATA connected all are NTFS formatted I'm using HD tune to check the transfer rate. On a fresh startup the transfer rate of the 500gig drive is around 78 MB/sec. This stays that way until i start to copy files to anywhere from this drive. I start copying any big file or collection of files and windows starts by saying it needs about 3 minutes to finish. But after 1 minute the time starts going up to 45 minutes. If i then abort the copying and go back to hd tune, i check the transfer rate again and then it's 3.8MB/sec. This stays that way until i reboot. I've tried several ways to solve this, all to no avail: Off course, spyware and virus sweep: nothing checked all cables :OK checked defragmentation: OK tried different connections on the Motherboard: nothing used the devicemanager to remove the harddisks and let windows reinstall: nothing. used the devicemanage to remove the sata controllers: nope Tried to find another driver for the controllers:nope Tried finding the same problem on google and forums: none found. Tried finding any weird settings in the BIOS: seems ok I also saw the same problem on my 250 gig drive (the WD). That would lead me to think it's not the drive itself that causes the problem. The 500gig drive is 2 months old. Also, since the problem occurs some time into the copy operation, it kinda looks like a piece of memory or buffer is filling up and doesn't empty or something. I'm only guessing there since i don't know a lot how this works exactly. i'm running out of ideas here, can anyone help me?