Symptom:

• You're domain is hosting on a one of our servers with Plesk 8.2
• You've select php5 as your php version
• when you try to access a php page (www.mydomain.com/somefile.php) you get 404: Page not found error

Resolution:

Please see the following KB article, specifically the section about Plesk 8.2 and php5... it provides information on changes necessary to make php5 properly work:  Using a custom php.ini