Hi all, I am a webmaster of a good vacation rental site sisnce last two year .It has now pr4 and yesterday it was ranking good in google ,yahoo and msn for all my main keywords. Last night I found my site "Reported Attack Site" by my mozilla browser . and today i see that not a single keyword of my site is ranking in google and yahoo in top 200 .and When i am serching for that query in google site:mydomain.com than results shows all the page are index by google but not cached .my PR is still 4 and index by google ,yahoo and msn and in MSN ranking is still same till now when i see more details provided by my browser then it is telling me like that "What is the current listing status for Mydomain.com? Site is listed as suspicious - visiting this web site may harm your computer. Part of this site was listed for suspicious activity 1 time(s) over the past 90 days. What happened when Google visited this site? Of the 8 pages we tested on the site over the past 90 days, 8 page(s) resulted in malicious software being downloaded and installed without user consent. The last time Google visited this site was on 2009-04-14, and the last time suspicious content was found on this site was on 2009-04-14. Malicious software includes 8 exploit(s), 3 scripting exploit(s). Successful infection resulted in an average of 3 new process(es) on the target machine. Malicious software is hosted on 2 domain(s), including peskostruikaz.com/, beebest.cn/. 1 domain(s) appear to be functioning as intermediaries for distributing malware to visitors of this site, including fabiomotor.cn/. This site was hosted on 1 network(s) including AS13767 (DBANK). Has this site acted as an intermediary resulting in further distribution of malware? Over the past 90 days, thinkrentals.com did not appear to function as an intermediary for the infection of any sites. Has this site hosted malware? No, this site has not hosted malicious software over the past 90 days. How did this happen? In some cases, third parties can add malicious code to legitimate sites, which would cause us to show the warning message." so please guys tell me what the actual problem is ..? and how can i solve this problem?
You likely have had third party scripts installed in your website code without you knowing it. You need to completely remove such scripts. Once it is all clean, in Google Webmaster Tools you can submit a request for Google to check if the problem is resolved. If you can't fix this problem yourself, you might have to hire someone to clean your code for you. I have recently dealt with this problem too. It is a pain in the ass. It just shows how important server security is. I will likely move my sites to a new web host soon.
Interesting question, at first sight I would also look at malicious code, is the template custom made or did you use a free one?
Most likely your site is hacked. Check your .htaccess, I see a lot of people hacking wordpress and joomla sites to modify .htaccess to point to a malware site. You should make sure you have removed any redirects or malicious javascript code and submit a reinclusion request using google webmaster tools.