hard drive keeps dissapearing while in use

[ONESHOTKILL]

I bought a couple 2tb samsung hard drives which i connected with a pci sata card,i installed and vista found them straight away,formatted,and started to use them but if i transferr allot of data to them,after about 10 mins they dissapear then come back.i checked event logs and i am getting these

The device, \Device\Harddisk2\DR2, is not ready for access yet.

The device 'SAMSUNG HD204UI SCSI Disk Device' (SCSI\Disk&Ven_SAMSUNG&Prod_HD204UI\5&2ac52cab&0&000200) disappeared from the system without first being prepared for removal.

The Portable Device Enumerator Service service entered the stopped state.

{Delayed Write Failed} Windows was unable to save all the data for the file \Device\HarddiskVolume2\ The data has been lost. This error may be caused by a failure of your computer hardware or network connection. Please try to save this file elsewhere.

when i am transferring my system goes laggy and sound skips with winamp
my system is x2 245 2.9ghz,4gb ram ,windows vista 64

 

[ONESHOTKILL]

i transferred all my mp3s over,200gb and all went over fine,but if i transfer any big files my music starts to skip then after about 5 mins the drive goes offline and i start getting errors,the pci card i am using is just a cheap card from ebay a sata pci SIMT173,the odd thing is its not like its using all cpu and memory recources so no idea why my sound starts skipping

 

[Sierry]

the pci card i am using is just a cheap card from ebay a sata pci SIMT173

This is exactly it.

The drivers for the card will be shocking or none existent. I had the same issue with the SIL680 motherboard drivers for my external WD hard drive and only when I removed them and used the windows 7 common ones were the issues resolved. Try a different card or connect it directly to your mobo and see if the issue gets resolved that way.