After highlighting text to be replaced within Word 2003 and typing the replacement text, or using CTRL-V to paste replacement text, the highlighted text is not replaced. Instead, the next text is inserted after the highlighted text. Interestingly enough, this problem also occurred when I had Office 2003 installed on my previous computer, before transferring the software to my current computer. After Office 2003 has been installed on the computer it works properly for a month or so, but then this problem occurs. This does not occur in other programs such as Internet Explorer when typing messages for my Yahoo Mail account. Have I accidentally pressed a wrong button somewhere along the line, which triggers this behaviour, or is there something wrong with my copy of Office?

Since the problem only occurs a month after the software has been installed, this indicates that the software itself should be alright but it is likely a configuration change to the computer is causing this behaviour. If the software itself was faulty, it would not work at all (as opposed to only partially working). The most likely cause of this problem is a configuration setting in Word, known as “Typing Replaces Selection”. This option controls whether selected text will be overwritten when typing or pasting replacement items with the text selected. To disable this option, go to the “Tools” menu > “Options”. In the window that appears, click the “Edit” tab. Untick the option “Typing Replaces Selection”. Click OK, and now you should be able to replace text by typing over the selected (highlighted) text or pasting text over the selection.

The question still remains as to why this option is enabled. There could be several explanations for this problem, including a hotkey setup on your computer which has accidentally been pressed, triggering this option to be enabled, or alternatively perhaps a Word add-on or macro which has been installed is disabling this option for a particular reason. Should this problem occur again, try to determine what was the most recent change you made within Word to see whether you can narrow down the problem to a particular installation or configuration change. In any case, should this problem occur again, you simply need to disable the “Typing Replaces Selection” option to fix the problem.