In Control Panel, select 'Accessibility Options' and make sure the options
on the 'Keyboard' tab are unchecked. The 'FilterKeys' option is probably the
most likely culprit.
BTW: This newsgroup is for questions about Microsoft Access, the database
program. General operating system questions would be best asked in a
newsgroup dealing with your version of Windows. For example try this one if
you are using Windows XP ...