That sounds just like the problem I am experiencing. However I get this error mesage in ma Apache logs:
/usr/libexec/ld.so: Undefined symbol "_PQsetdbLogin" called from httpd:/usr/lib/apache/modules/libphp4.so at 0x40307394
Apart from the DB functions PHP works perfectly. Sorry to say I have no solutions for the problem. Hopefully someone reading this will have.
/Martin