Error - ''boot_unmountable_drive'' when installing XP

For those who are getting this error when you try to install WinXP on a motherboard that has UDMA 100 Promise Controllers you need to do the following in order to get XP to install correctly if your hard drives are connected to the UDMA 100 controller.

Now there are two ways to get XP installed, the first one I am going to mention is the easiest way and the second is a bit more complicated but will work never the less.

#1 - Easiest Way

I have an Asus A7V motherboard and I have run into this more than once. What you need to do (this is the easiest way to do it that I have found) is to move your hard drives cable off the UDMA 100 controller (normally color coded blue) over to the UDMA 66 master controller on the motherboard. Once you have done that make sure your PC still boots into your current OS correctly. If it does then start your XP install or upgrade. Everything should be fine. Now, once XP is up on My Computer and choose Manage. Look under Device manager and you will see an error with a yellow exclamation point on it. Right click on it and install the Promise Drivers. You can download them directly from here - ftp://ftp.promise.com/Controllers/IDE/Ultra66/UltraFamily/U100d160b32.zip

Once you have the drivers installed re-boot the system and make sure the yellow exclamation points are gone and the promise drivers are listed under SCSI devices, if they are then turn off your system, move the HD's back to the UDMA 100 controller and boot it up. That should fix it.


#2 - Fresh Install

If you plan on installing XP to a freshly formatted hard drive the easiest way I have found to do this is to use the above method but for those with only one UDMA 66 controller on there motherboard you may need to do the following:

- First use the URL above and download the Promise drivers from the Promise website.

- Second you need to extract the drivers to a floppy or to the partition on your hard drive that XP can see (FAT32 works great for this) but there is a trick to this in order to make XP see the drivers. Once you extract the drivers the promise drivers automatically make folders for each individual OS (see screen shot), what you need to do is move the files from under the Win2K directory to the of the Promise Folder. So you take the three files under the Win2K folder and copy them, don't move them but copy them to the root of the main folder where you extracted the Promise drivers to (if you don't see three files go to Tools/Folder Options/View and check "show hidden files"). The three files you need to copy to the area are:

- Ultra.cat
- Ultra.inf
- Ultra.sys


Now that you have all the files in the copy them to a floppy, reboot (if needed) and start your install of XP.

Now pay attention here - at the bottom of the very first blue setup screen you will see a prompt to hit F6 to install third party SCSI or RAID drivers. HIT F6 A FEW TIMES NOW!!! Now it might take a couple of seconds but you should be prompted to insert your drivers into your floppy drive. Do so and choose the Promise ATA100 controller. Keep this disk handy as you will be prompted for it one more time during the install.

Once XP has the drivers and loads them successfully XP should install just fine, well at least as far as the controller goes.