Today is April 3, 2012
It's now 7 or 8 months after the original poster made his comment(s). The problem still exists. At least, it exists for me occassionally. The 'red question mark' (text) is totally non-interactive, even if/when it does appear. The in-field 'pop-up' quest completion box is inconsistent in behavior, and doesn't always work.
Having to resort to <ALT-L> is not really a solution to the issue.