Do Multiple Domains Cause a Problem?

Does use of multiple domains get you killed in SE position.

[pkropp]

I run 3 websites with KEYWORD1KEYWORD2.COM then another site with KEYWORD1KEYWORD3.COM then another site with KEYWORD1KEYWORD4.COM. Our sites sell about 40 differant products that all solve similar problems, but in differant ways. The sites all have similar content but not the same content. I have linked all the sites together.

Have I committed spamming unknowingly. I am not an SEO just an employee who has been given the task of being webmaster. Our sites have long been in Google, sitting as high as #1 for about 40 keywords. As of 3 weeks ago I was #6. Now as of today I am not in the top 10 PAGES.

If I have created a horrible issue here, what are my chances of being able to fix this or do I need new domains and just start over.

Page Rank on all these sites are 4 and all the sites are in the results when I type domain.com.

Paul

[Magnum_PI]

Don't interlink the sites and consider 301 redirects to focus on a single site with unique content.

[piskie]

Keyword rich domain names are not a significant gain in the major search engines and that appears to be your companies motivation to run 3 very simmilar sites with the inherent risks it will bring.

I agree with Magnum_PI do one site well, then just because they are there 301 redirect the other two.