Other than what Kache answered, the trick to prevent further changes/reversions (e.g. if you accidentally attempt to change it from any Windows settings) is to simply DENY "full control" to everyone within the registry.

Dummies Step-by-Step:

• if you are using RegEdit, right click on the "00000010" key on the left navigation tree
• select "Permissions..."
• for each and every "Group or user names" item, check all the boxes under the "Deny" column
• click "OK"
• repeat for the "00000070" key on the left navigation tree

Registry permission changes take effect immediately (try setting or resetting the IME toggle key now - it will not work). As stated in the original answer, for the actual CTRL-SPACE key to be "deactivated" (for the purposes of toggling the IME), you will need to log out and log in again.

Other than what Kache answered, the trick to prevent further changes/reversions (e.g. if you accidentally attempt to change it from any Windows settings) is to simply DENY "full control" to everyone within the registry.

Dummies Step-by-Step:

• if you are using RegEdit, right click on the "00000010" key on the left navigation tree
• select "Permissions..."
• for each and every "Group or user names" item, check all the boxes under the "Deny" column
• click "OK"
• repeat for the "00000070" key on the left navigation tree

Registry permission changes take effect immediately (try setting or resetting the IME toggle key now - it will not work). As stated in the original answer, for the actual CTRL-SPACE key to be "deactivated" (for the purposes of toggling the IME), you will need to log out and log in again.

As I am low-ranked, I am unable to add a comment on Kache's answer, so I have to "answer" the question.

Other than what Kache answered, the trick to prevent further changes/reversions (e.g. if you accidentally attempt to change it from any Windows settings) is to simply DENY "full control" to everyone within the registry.

Dummies Step-by-Step:

• if you are using RegEdit, right click on the "00000010" key on the left navigation tree
• select "Permissions..."
• for each and every "Group or user names" item, check all the boxes under the "Deny" column
• click "OK"
• repeat for the "00000070" key on the left navigation tree

Registry permission changes take effect immediately (try setting or resetting the IME toggle key now - it will not work). As stated in the original answer, for the actual CTRL-SPACE key to be "deactivated" (for the purposes of toggling the IME), you will need to log out and log in again.

Other than what Kache answered, the trick to prevent further changes/reversions (e.g. if you accidentally attempt to change it from any Windows settings) is to simply DENY "full control" to everyone within the registry.

Dummies Step-by-Step:

• if you are using RegEdit, right click on the "00000010" key on the left navigation tree
• select "Permissions..."
• for each and every "Group or user names" item, check all the boxes under the "Deny" column
• click "OK"
• repeat for the "00000070" key on the left navigation tree

Registry permission changes take effect immediately (try setting or resetting the IME toggle key now - it will not work). As stated in the original answer, for the actual CTRL-SPACE key to be "deactivated" (for the purposes of toggling the IME), you will need to log out and log in again.