Resolution chang size after rendering/converting

I have a really strange problem this time.

Every week I upgrade my Blender to latest version from Graphic All today I run att Blender 2.58.1 r37787 64 bits.
I use a brand new iMac Intel 10.6.8 21.5 inch 64 bits
I use Vimeo Plus to store my converted blendfile at.

I never change the resolution 1920x1080 (Default)

After rendering I open up Vimeo + Choose a file to upload + Flash-uploader (I have the latest Flash at my iMac) + File+ Blendfile + and press upload/converting. (My Blenfile.avi have everytime codec H264 x AVI

I am always use HD at Vimeo, But this HD disappeared suddenly and I wondered why, until Vimeo Support informed me that I used the wrong size 960x540 ???

I dont understan why. This never happens before.

Do you know how to solve this problem.

Thank you

You rendered to 50% of 1920 x 1080 = 960 x 540

OK, but I have always use this settings 50% and not have any problem before. I vill try with 100%.