photo stream problem

my photo stream worked perfectly from i phone to computer , but I have just returned from holiday and only half my pictures have downloaded into the folder on windows on my laptop, when i go into the folder it says icloud is not enabled, it is enabled on my phone, so i checked settings on computer.

strangely it will not let me check the box next to photo stream and apply on the computer , each time i do it i return to look at settings and the box is unchecked again, so the rest of my photos havent gone into the folder on the computer

I dont understand why it sudenlt doesnt work, and why it is unabled. so i bought extra storage, didnt resolve.

it still keeps saying photo stream unabled.

any one know how i get it stay enabled on my computer , the phone is fine, all settings are right