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Windows 7/Upgrading Drive C to Larger Capacity


A W7 desktop with 2 drives C and E.
75 GB C contained all my programs. 500GB E contained all my files,
I added a 300GB Drive L to replace drive C.
I cloned Drive C to Drive L and removed Drive C and disconnected Drive E to determine if the replacement drive would boot.  It booted successfully, and in Disk Management, the old Drive L is correctly labeled C.
The problem:
When I replace Drive E, I receive the error message:
toskrnl.exe is missing". I cannot proceed.
It appears that the system is attempting to boot from Drive E.
Do you have any insight as to how to correct the problem. Disk Management correctly shows the drive as Drive E.
Any insights would help.
Happy Thanksgiving.

ANSWER: Hello Nicholas

There are a few things you are going to want to check. Starting with the BIOS settings. Making sure you have the Hard drive Boot order set to the correct hard drive. In fact when you choose the boot order first you typically can choose from CD/DVD or HDD (hard drive) or Network, etc.  I will start with CD only while installing the operating system and once installed I will change this first one to HDD only.. and disabling all the rest.
Next you need to choose the boot order since you have now selected HDD as the first boot device, you will also have the option of which hard drive in order so be sure the one you want as C is the drive that is listed first.

This is of course based on a SATA hard drive, since SATA drives you can plug them in to port 0, 1, 2, 3, etc and it doesn't matter if the drive you have plugged in to port 0 is in fact Drive C since the bios setting is what is actually read. This allows for hot swapping of the drives as well.

If your hard drives are IDE drives then you will need to make sure the jumpers are set to master and slave accordingly (best method) although you can choose CS (Cable Select) but if you do then you will need to make sure that Drive C hard drive is on IDE 0 and the data drive is IDE 1

Finally, what you are going to need to do if after you have checked and confirmed all of this, is to make sure BOTH DRIVES are plugged in and then insert your windows CD and perform a REPAIR for starting your computer. This should fix the boot codes within the master boot file.   Yes, you can go in and edit this but it is hit and miss and much more work since you are always going to better to allow windows to repair this itself.  To do this, now that you have set your bios to boot to hard drive first, you will need to press the appropriate BIOS key to choose drive select upon power on (usually F11 but can be F12, F10, so check your bios/motherboard specs)  Alternatively you can go in to your bios settings and set the first boot device as your CD drive with HDD as the second.  But once you have fixed this problem, I suggest setting the HDD as the first boot device to prevent any bootable cd from causing your system to not boot as a result of leaving the cd in the drive.

Use the following link to help with the boot loading issues as a reference as well:

Hope this solves your problems.


Mike Dacre
follow me on twitter @tpsconsulting

---------- FOLLOW-UP ----------

Thanks for your professional and detailed response.
I plan to access BIOS, but have been unsuccessful.
I have an ASUS motherboard and the User Guide indicates to press Delete or F8 to bring up the BIOS screens. Neither work in my case. I suspect that it may have something to do with my keyboard. I plan to buy a new one. Hopefully the new keyboard that will get me to the BIOS screens.
Thanks again for your help.
Have a good day.

Hello again Nicholas

It will be the DEL key as F8 is used for windows boot menu. You are probably right about the keyboard. If it is a wireless keyboard then it may not work since the usb is not powered up immediately which would be what is needed to power the keyboard wireless transmitter/receiver  and send commands to the motherboard. If your keyboard is usb however and it is plugged in to the motherboard directly (not through a hub) then it should work. If your keyboard has a light on it and it comes on when you turn on the computer then that should be good.  When you turn on the computer you will need to start pressing the DEL key quite quickly and about every 1 second .. if you see it starting to boot then you missed it and you will need to power off again.


Mike Dacre
follow me on twitter @tpsconsulting

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As I have been volunteering in the 'windows' category since the inception of AllExperts, which has now moved to numerous windows categories. I will therefore be happy to answer any Windows 7,8 and 10 based question. What can't I answer? Not much, as this is the main reason I volunteered here, because I am hopeful the questions I can not answer will allow me to investigate the problem so that I can answer it. The TIPS and SOFTWARE support through my website at can also be of some help.


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I grew up with computers, from the first Apple IIC, back when Bill Gates was a student himself! For the past 17 years I have been providing technical services from building computers to constructing complete control rooms. Working with CTV I have helped produce the 1994 Olympic Games in Lillehammer, Norway. Later, designing and construction of "instant replay control rooms' for the Big Screens found in Stadiums and Coliseums.

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