Problems with Google

[Eagle Creek]

Hi,

I'm not quit sure if this is the right forum I think it's most fitted for the job.

My problem:
Five years ago I made a website with a domain name. (abc.nl)
Two years later I added another domain (def.nl)
One year later I added another domain (def.eu).

My website always had a lot of visitors, more then 10.000.000 an month, with 100.000 unique. They came at my website primarily using Google and one of the above domains. abc.nl has the most Google hits, then def.nl then def.eu.

Since December 29th we made a change in our domain configuration. Instead of having abc.nl being the main domain and def.nl/def.eu being aliases, we changed the configuration to:
def.eu -> main domain
abc.nl / def.nl -> pointer.

This means, every user who uses an old domain name automatically gets redirect to def.eu. The problem is: the amount of visitors has dropped like a brick. I don't get any Google bot anymore at my forums and new posts aren't being indexed. Even worse, it looks like old posts can't be found anymore also.

I think Google thinks I'm using some kind of bogus redirect to infect my visitors, or whatever. I hoped this wouldn't happen because my website internally always used the def.nl links everywhere and def.eu a lot.

What to do about this? I temporally changed the domain name configuration back to how it was before December 29th but I would like to have some advice on this.

(PS: I also posted this at vb.com).

Edit:
I just changed the domain names and Who's online tells me:
13:26 Yahoo! Slurp Spider
13:18 AskJeeves Spider
13:27 Google Spider
13:22 MSNBot Spider

I was thinking of redirecting the domain with some kind of 301-message (http://en.wikipedia.org/wiki/URL_red...atus_codes_3xx) so Google will know it's a valid redirect. Will that work?