I also use the definition as used for powers. So if the effect takes place at DEX 1 for example, next round the effect stops if it lasts for 1round.
However, my impression is that the rules are not clear on how long 1 combat round is, when the effect starts inside the combat phase(see the orc example in the first thread). This may cause problems to critical situations were the party is in danger. Please, give a clear definition or clarification according to the official mechanics to don't disagree with my party all night...