I had used
jQuery('#id').attr('readOnly', 'readOnly') set the readonly property of text box and used
jQuery('#id').removeAttr('readOnly') to make the text box again but then found that
"removeAttr" did not work in IE7, the textbox was still not editable.
Searching a bit found the
.prop() jQuery method. Using
jQuery('#id').prop('readOnly', null) resolved the IE7 issue.