Smarty无法访问templates_c中的编译文件

I just installed a cms system but I'm getting the following error:

[function.include]: failed to open stream: No such file or directory in
 /home/postertest/domains/buyuseraccounts.com/public_html/libs/Smarty.class.php 
on line 1283

When I check the templates_c file, the requested file is however there:

%%45^45E^45E480CD%%index.tpl.php

When i try to access the compiled file directly through the browser, it however gives a 404. When I rename the file (%%45^45E^45E480CD%%index.tpl.php) I can access it. It therefore seems that the error is caused by by Apache.. What should i do?

UPDATE

Actually, now that i test it out to another CMS on the same server, it appears there i can't access the files underneath templates_c directly as well. However there, Smarty doesn't cause any error. I tried putting the smarty distribution of the working cms to the non-working but still it gives the same error.