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We all use editing facilities to change a line of text as we are entering it. There are two principal editing modes within a line, a) "insert mode" which inserts non-editing characters at the point of the cursor, and shuffles text to the right, and b) "overwrite mode", in which non-editing characters simply overwrite whatever character the cursor selects.

Overwrite mode IMHO is left from the days of green-screen CRTs. The only use I have ever found for it is drawing 2-D pictures in ASCII, which I quit doing back in the 80s when real drawing tools became available.

Windows (stupidly IMHO) offers overwrite mode toggle-enabled by use of the INSERT key on the keyboard. (I'd guess Linux/Unix likely follow suit in the usual Windows-envy). I don't ever hit that button because it just puts me in overwrite mode.

However, as I'm typing sometimes Overwrite mode suddenly happens. I think it must be some strange combination of ALT/Windows/CTRL/SHIFT and some other key, or two standard keys depressed in time nearby. Does anybody know what the alternate key sequence is so I can try harder to avoid it? Is there a way to tell Windows to simply stop using Overwrite mode?

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It appears that Shift+Numpad0 puts one in insert mode. I think this is the actual cause of my problem. (Does anybody on the planet actually use insert mode?) – Ira Baxter Sep 10 '14 at 10:57
I'd like to add (even though this is off-topic) that upon experimentation, I found that it isn't just Shift+"Numpad 0". Shift+Numpad seems to disable the effect of Num Lock, so we also have Shift+period (delete!), 1, 2, 3, 4, 6, 7, 8, and 9 all doing their other equivalents. I wonder if this is specific to Microsoft Windows, or generally supported by other software, or perhaps a keyboard-thing (that requires no special software support, because it is handled by keyboard scan codes). – TOOGAM Oct 6 '15 at 18:34
The accepted solution didn't work for me on Windows 8.1 (though a related question about how to disable Caps Lock did). – AlainD Mar 24 at 23:00
up vote 10 down vote accepted

How to Disable the Insert Key in Windows

Almost anyone who has used a wordprocessor has accidentally hit the Insert key and overwritten when they thought they were editing. This article describes a simple way to disable the Insert key on your keyboard.

Whenever you press a key, a windows message is created, which contains a key code that uniquely identifies the key pressed. Programmes (like Microsoft Word) look for keypress messages and take actions based on the key code in the message. By mapping the insert key press event to null, windows send a message containing null for the key code when the Insert key is pressed. Programmes receiving the message, therefore, do not perform the action associated with an insert key press event, freeing you from having to worry about overwriting things again.

  1. Go to Start → Run → regedit
  2. Go to HKLM\System\CurrentControlSet\Control\Keyboard Layout
  3. Right-click on the right half of the screen and choose New → Binary Value
  4. Name the new value Value Scancode Map
  5. Enter 000000000000000002000000000052E000000000
  6. Close regedit
  7. Reboot.
  8. Optional: you can take the Insert key off of your keyboard when done.

If you do this with Windows7 regedit, you have to enter the hex value in rows of 8 bytes, like this:

Value Data:
0000    00 00 00 00 00 00 00 00
0008    02 00 00 00 00 00 52 E0
0010    00 00 00 00


Registry file (.reg) to apply the fix as described above

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Keyboard Layout]
"Value Scancode Map"=hex:00,00,00,00,00,00,00,00,02,00,00,00,00,00,52,e0,00,00,00,00

Put the above text into a file with a .reg extension (e.g.: disable-insert.reg), and double click.

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I never gave any credit for this. My bad, so "accept" now. – Ira Baxter Feb 26 '14 at 4:08
This can be done less manually/dangerously by using SharpKeys - see dangph's answer below – rattray Apr 23 '15 at 7:49

The 0 key on the numeric keypad becomes insert when num lock is off.

When you type something in an MS-DOS application and go back to the middle of the phrase and press TAB, you switch to overwrite mode.

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You mean the 0-key on the numeric keypad is the insert key when num-lock is off. – Dennis Williamson Aug 30 '09 at 13:07

Use SharpKeys to disable the Insert key. It is easier and safer than doing the registry hacks yourself.

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I discovered SharpKeys a couple years back (look at date of question) but didn't remember I asked this question. So, +1 for answering with an excellent answer. Guilt made me accept (just now) a much older answer which I used before I found SharpKeys. – Ira Baxter Feb 26 '14 at 4:10
@Ira, no problems, thanks for the upvote :) One thing that SharpKeys won't do, I've just discovered, is it won't disable Shift+NumPad0. I recall that there is a hotkey editor out there somewhere. That might do the trick. But I never hit that key combination accidentally, so it doesn't affect me. – dangph Feb 26 '14 at 4:21
Over long usage (note the age of this question), I've discovered that I do hit "Shift+NumPad0" by accident occasionally. The fact that this is really rare means it takes me some time to recognize it, and, since I'm in insert mode with the insert key disabled, it isn't obvious how to get out again. Eventually shift+Numpad0 comes to mind. The rare events are the worst to handle. So, I need a stronger answer. Sigh. – Ira Baxter Sep 10 '14 at 10:55

Just figured this one out... Shift+0 on the numeric keypad. I guess I must accidentally tag it while speed typing often enough. Has been throwing me for a long time.

While my addition above may be helpful to some, that wasn't my problem. Anyone stumbling here, if this happens pretty much no matter what app you may be in (i.e., not solely to do with editing in MS Word), save yourself the aggravation of searching to the end of the internet like I have...

My personal definitive conclusion is that there is no "other magic key combo" for toggling insert overwrite, period. So therefore the only remaining possibility is that in the course of rapid typing, either due to an imperfect/sloppy stroke combo OR a bounce on the keyboard aiding in such, an unexpected encoding is generated that happens to always trigger ins/ovr toggle. I gather from my personal research that it is more likely due to a keyboard/hardware flaw than a software flaw. If it was a software flaw I think we'd see more posting on the net about it.

I am going to finally try the regedit suggestion posted, and simply try to get over it now.

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Go to File - Options - Advanced - Use Insert Key to Paste - It will still be used but for a much more practical reason and you will notice when you have pasted something you don't want :-)

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