Suexec shouldn’t be causing these problems if i5s setup right.. I use suexec on all of my servers. Member servers. servers. Posted 6 days ago servers.
Sounds to me like a permissions issue… make sure that the owner and group are correct on all the files/folders in your docroot. Also make sure the permissions of the files/folders are correct. Like the docroot folder is 751 or 755, the php files are 644, and check the php interpreter.
If you can, set up logging for Apache and that will tell u quickly what u need to do. Finally, it may just be a simple matter of modifying your httpd.conf file settings like max servers. Or it could be that the system is setup to allow the nobody user that runs Apache to have much larger limits like how many processes and files are allowed open at one time- when using suexec the server will run as the user who owns the docroot, and that user might have much more restrictive limits.
See limits.conf. There is a lot of info about this at http://httpd.Apache.org/