529423 Immediate fix for malware on dedicated server

Hi, We run Apache on Linux. Dedicated server at olm.net. 5.2.9 (apache2handler), 4.1.20 mysql AFTER placing an order, we get this message: [login to view URL] contains content from [login to view URL], a site known to distribute malware. Your computer may catch a virus if you visit this site. "[login to view URL]" has nothing to do with us. It's apparently a hacker. We had some issues in the past few months with our htaccess being modified. But I just checked and it looks ok. 1. Figure out what is causing this message 2. Remove the malware if it exists 3. Find the vulnerability being exploited if possible and fix it or, at minimum, tell us what needs to be fixed. I assume there are tracks in the log files. 4. I need you to get this done today 10/13 during the daytime and communicate with me on skype if need be, although I'm not a technical person so I don't have a clue. 5. I need this done urgently as a priority project