I have an alienware m5790 laptop with a VIA 6421 SATA RAID controller that allows 2 hard drives. My boot drive is a Seagate 2.5" 100GB 7200rpm drive and I recently replaced the second drive with a WD 320GB 5400rpm 2.5" drive. Until the installation of the new drive things were fine. I was able to successfully install the 320GB WD drive and use it. However, recently the drive would often freeze when XP runs for some time. If I try a hard reboot, the bios takes forever to POST - all sign of a typical drive failure. However, I am able to boot the laptop again after a significant gap (overnight typically) and every thing works hunky dory for a long time. Would there be another reason why the drive seems to "freeze" every so often? I have noticed the drive disappear in disk management until I hit "Rescan" and the drive is discovered again. Unfortunately I can only do this if the laptop hasn't crashed yet already. Thanks in advance.

Your BIOS may not support harddrives larger than 137GB. Look at the link below for further explanation. If your BIOS is not 48bit LBA compliant and you install a large drive WinXP may seem to be OK but eventual data corruption will occur. http://www.48bitlba.com/index.htm

But the laptop had 160GB drives in its original configurator on Alienware (including a 2*160GB RAID 0/1 option)? How would they advertise those drives if it had a 48-bit LBA issue? Moreover, shouldn't the 48-LBA problem also restrict my hard drive capacity to 137GB? I am able to see the full 320GB without issues. Moreover this laptop is relatively new (2007). I don't think 2007 laptops would have a 48-bit LBA issue?

To answer your questions in order. First you now have a 100GB boot drive. I naturally assummed that was the original drive. If the laptop came with 160GB drives then the BIOS must be 48 bit LBA compliant. As far as the 320 showing watch the startup screens and see if the BIOS is actually seeing the entire drive and identifying it by model (part of the model number is drive size). WinXP running SP1 or later may see the entire drive even if the BIOS is not compliant. This situation can occur if the new large drive is not a boot drive and has been installed after the OS is running. WinXP will act as though the drive is fully compliant even though it may not be. Assumming all is well with the startup screens then 48bit compliance isn't the issue. Are you running some type of RAID configuration now?

Bios can see the drive correctly during POST. I don't have any raid setup, just running it in Sata mode.

Sounds like your hd is bad. Have you tried another HD and see if it works fine? If it does then it's the HD.

Do you have all the drivers for the MBoard installed?