A CNAME-record cannot exist with any other records for the same name, because a name cannot both be an alias (CNAME) and something else at the same time.
If you try to create a CNAME-record for the name of the zone itself, you will always encounter this conflict because a zone always has at least a SOA-record and typically one or more NS-records with the zone name:
Then why does your default template attempt to create a CNAME as follows; <www.domain> CNAME <domain>
The real issue here as I have now seen is that you are doing a permanent 301 redirect - for what purpose? The INDUSTRY standard is that the www is handled by a simple 'A' record, ie: www A <ip> - why do parallels insist that Control Panel is responsible for deciding what is created in the DNS records when there are times certain types of hosting require non standard configurations.
In relation to actually finding anything in PLESK 11, the change from 9 to 10 was bad enough and you still did not listen to your clients and version 11 is a damn nightmare in design and layout. What ever happened to the KISS principle - 'Keep It Simple Stupid' and the expression, "If it ain't broke, don't fix it".
As a user of PANEL for a small hosting company, it is taking longer and longer to set up a simple domain - for example, setting the hosting default (<domain>) or <www.domain> SHOULD BE ON THE PAGE YOU CREATE THE DOMAIN - ooops, sorry, you can't just create a domain any more, you have to create a 'SUBSCRIPTION' and then you have to click on 'domains', go to 'websites and domains' and if you are luck to see the tiny small text 'hosting settings' you stand half a chance. But then you decided on the 'Websites and Domains' Page to HIDE 1/3rd of the page that allows access to the DNS settings.... surely DNS belongs on the HOSTING SETTINGS page as without DNS you are not doing any hosting, regardless of what you have created in a 'SUBSCRIPTION'.
PLESK 11 is all over the place, it is untidy, confusing, difficult to navigate and clunky - and that is from a professional point of view, god only knows how end users are ever going to find anything and set up their websites....!!!!!
When are you going to permit the creation of a correct 'spf' record in the DNS?