Please note that securing a hosting account requires a proactive approach. To get rid of this issue, I would request you to:
First, check your website for any malicious contents at:http://sucuri.net/, then follow the below steps.
1. Scan your local computer using an updated Anti-virus.
2. Then ask your web developer to conduct a thorough audit of your account to remove any vulnerable scripts, files/folders which are not related to your website contents.
3. Download all your web data locally and scan it using an updated anti-virus software.
4. After you have done it, remove all the existing website contents from the server and re-upload the scanned data.
5. Make sure all scripts (your website applications) are updated to their latest versions to avoid any vulnerabilities from being exploited.
6. Also use 'http://www.pctools.com/
Once done, please re-submit a website review to Google using the below Google webmasters tool:
Once the site is examined by Google and it is considered as malware free, the malware warning will be removed from your site.