Convert Path To Marquee

I've been having an intermittent problem with Fireworks that is driving me crazy...

If I use the PEN tool around an area of an image so I can cut it out. 

I click "convert path to marque".

Next, I click CTRL-C to cut the part I want out (which works 8 out of 10 times).  There are times it when the CUT does not work and I am not able to extract the part of the image I've selected.

Any ideas?

Thanks all!