This is what it says in the OP25A:
www.cic.gc.ca/english/resources/manuals/op/op25a-eng.pdf
An allowance for a reasonable period of vacation time will generally be made in calculating the period of qualifying work experience (e.g., a two-week period of paid vacation leave within a given 52-week period in which the applicant was engaged in qualifying work experience). An allowance for normal vacation time during a period of qualifying work experience cannot be used as a substitute or proxy for meeting the in-Canada element of the work experience requirement (i.e., work experience obtained outside Canada will not be considered as though the applicant had been on a period of vacation in order to be counted as part of the period of in-Canada work experience). While officers will account for a reasonable period of vacation time in calculating the period of qualifying work experience in Canada, each application is considered on its own merits with a final decision based on a review of all the information available to the officer at the time of decision.
I do not interpret anything in this language as saying you can't count your two weeks of vacation if you travel outside of Canada. But given that it is also a relatively new rule, and a tad convoluted, I would not be surprised if a VO did interpret it that way.
It does say you can't use "vacation" to cover for a work trip outside of Canada. So most likely, applicants have been trying to do that, reinventing work trips as "vacations," and VOs have become suspicious of those vacations (perhaps in singh178's case?). So in the better-to-be-safe-than-sorry category, you would be wise to work extra to cover ANY time spent outside of Canada.
For Nesa09, I think it's pretty clear that you cannot count that week in the USA.
But, AGAIN - if you're afraid that one week will make a difference in your application being accepted or refused, you are cutting it WAY too close. Work some extra time before applying...