domain name system - DNS redirect error (probably CNAME related)

I have this question. There's a lot of information out there but none of the things I tried helped and I am still unable to identify if it can be helped at all.

I have a site originally with a provider. Later I transferred the DNS to another web hosting site but the DNS settings are still visible on the original domain registrar.

So what happens is the site will display at www.domain.com but not when I put domain.com

I've checked the CNAME settings on both the original provider and the new one and appear to be correct.
I've also tried to enable forwarding using an .htaccess file and that failed too (although some other redirects seem to work well).

I can't identify where else to look in order to finally get domain.com working!
Could it be some sort of limitation on the new web host that forbids that sort of thing? (even though there is a CNAME setting present)

Any help will be greatly appreciated. This has been troubling me for over a month!

Thank you

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UPDATE 10/10/11

I am trying to make sense of all this. The domain is fineenergy.co.uk (or www.fineenergy.co.uk is the one that actually works)

By doing a NSLookUp I get much more results than www.fineenergy.co.uk

I think, as you said, either the A record or the CNAME records is missing but after checking the DNS settings I find that both records are there. In detail:
A Record
Host fineenergy.co.uk Points to 66.96.147.104
CNAME Record
Host fineenergy.co.uk Points to www.fineenergy.co.uk

Not sure what else I could add to that.
The only other thing I can think of is that these settings are ignored in favour of the original host's settings.

Any other suggestion would be very welcome.
Thank you guys for the help!

Answer

Without seeing the actual records, you will want to do a DIG (or NSLOOKUP) on the domain and look for what gets returned with and without the www.

This is how stackoverflow.com is set up. If you are missing either a CNAME or an A record for both the www and without, that is your issue.

stackoverflow.com.  1200    IN  A   64.34.119.12
www.stackoverflow.com.  1200    IN  CNAME   stackoverflow.com.

If you post the domain, we can better help. Also, this question should be on serverfault.com , I have requested it be moved there as it is not programming related.

EDIT: 10/10

Since you are seeing the A record, but the internet is not, it is possibly due to the domain pointing to the wrong name servers.

Name servers:
        dns1.fluent.ltd.uk        195.78.94.253

        dns2.fluent.ltd.uk        195.78.94.254

You mentioned switching web hosts, if that is not your current web host then you need to contact 1 & 1 AG and have them change the name servers over to your current web host so the internet sees the correct DNS records.