When using Word or Excel and I type the minus symbol, the symbol turns to a plus sign as soon as another character is typed. The only time this doesn’t change is when using cell references in Excel instead of text. Using a different keyboard does not fix the problem, nor does reinstalling Microsoft Office. The computer is running Windows XP.

This is quite an interesting problem, which I have not encountered before, especially because the problem is localised to Word and Excel. First, it is possible that for some reason an AutoCorrect has been set in Word and Excel, which automatically replaces instances of the minus character to the plus character. To check, go to the ‘Tools’ menu > ‘AutoCorrect Options’. In the window that appears, click the ‘AutoCorrect’ tab. At the bottom of the window there will be a table headed with ‘Replace text as you type’. Look through the list of entries to check whether there is an entry for the minus (-) symbol to be replaced with the plus (+) symbol. If found, select the entry and click ‘Delete’. You should also check the same settings in Excel.

The next possibility is that the keyboard layout in Windows has been incorrectly configured, so the computer thinks that keys on the keyboard are assigned to different characters. This is not as likely as the AutoCorrect scenario detailed above, since if the keyboard layout was the root cause then the problem should also be occurring across other applications. However, this is still worth checking. Go to the ‘Start’ menu > ‘Control Panel’ and open the ‘Regional and Language Options’ control panel (you may need to first click the ‘Date, Time, Language and Regional Options’ category). In the window that appears, click the ‘Regional Options’ tab. Make sure the ‘Standards and formats’ section is set to ‘English (Australia)’ and the Location is set to ‘Australia’. Click ‘Apply’ and then click the ‘Advanced’ tab. Make sure the ‘Language for non-Unicode programs’ is set to ‘English (Australia)’. Click ‘Apply’ and then click the ‘Languages’ tab. Under ‘Text services and input languages’ click ‘Details’. Make sure the ‘Default input language’ is set to either ‘English (Australia) - US’. This uses the English language, with the US keyboard layout. If this option is not available, click the ‘Add’ button to add the language. Then, under the ‘Installed services’ verify that the ‘Keyboard’ is ‘US’. Click ‘Apply’ and then click ‘OK’ to close the window.

If the problem is still not resolved after following these steps, please contact me again for further advice.