Philip Payne in an article published in New Testament Studies in April 2008* tackles the technical question of whether the negative used by Paul in 1 Timothy 2:12 implies one or two prohibitions in the verse. This is his conclusion:
"Consequently this oude construction makes best sense as a single prohibition of women teaching with self-assumed authority over a man.
This understanding fits the text and its context lexically, syntactically, grammatically, stylistically, and theologically. This single specific restriction perfectly fits the danger of false teaching by women in Ephesus. It does not contradict Paul's and the Pastoral Epistles' affirmations of women teaching nor does it prohibit women such as Priscilla (who instructed Apollos in Ephesus according to Acts 18:24-8 and later was evidently still in Ephesus) from teaching men, as long as their authority is properly delegated, not self-assumed. It simply prohibits women from assuming for themselves authority to teach men."
(* 1 Tim 2.12 and the use of oude to combine two elements to express a single idea, NTS 54 (2008) pp. 235-253 - Hat-tip to Evangelical Textual Criticism).