it was possible but it is not the reason
mine is also on a subdomain that i created 5 min ago ...
to see if it is the subdomain you can move all files to a other folder ( test for example) and put a index.php page into the site
put just this in the php file
Code:
<?php ehco "hello world"; ?>
if that page works , thent he subdomain works
if not , then you need to contact namecheap as probaly something went wrong with apache settings (virtual hosts )
if that is not the solution , then i guess you need to try to use a older version and see if that gives the same problem ( version 1.3.1 for example ) to eliminate the errors
but i still think it has to do with the cgi of apache , instead DSO , but unlikely that namecheap will change that (cpanel = php & suexec settings )
Greetings From PowerChaos