Windows 7: win 7 system image problem

hi all
i realise this may have been asked before but here goes.
i and reading off net seems others have a problem creating a system image to dvd,s.
windows 7 pro, i start the app then i get the message that could not complete through memory.
i have 250gb hdd with 185gb spare, in my computer i have my normal drive, and a recovery drive.
i have read 1 problem is if you have a reserved partition on hdd that needs 100mb & majority is full then system image will not complete.
but i have no reserved partition on hdd.
would it be possible if other moderators-gurus-members could jump onto this problem to find a resolve.
like said seems this is common problem a lot of people are having.

thanks in advance for any help given.