I had a similar problem. Our previous webmaster has used hidden text. Whilst our site remained in top 5 for about 2-2 1/2 years, earlier this year Google blocked it from the index saying that we had used techniques which violate the webmasters guidelines. I then personally checked each an every page and removed every evidence of hidden text and re-submitted through the sitemaps section. The site reappeared after about 3 months and shot back to top 3 position.
All was well up untill couple of weeks ago when it was again blocked by Google and they gave me the same old story.
Now I don't know what to do as I do not know which part of their webmaster guidlines the site is in violation of.
Any comments will be welcome.
Thanks
NAD
www.sportshospitality.com