[CentOS] Missing Dependency

 Problem:
    I am trying to update the php package PHP Version 5.1.6 on CentOS 
 release 4.8 to get rid of a script error:
 "PHP Fatal error:  Call to undefined function dom_import_simplexml"
 
 while running yum update php I get the following
 
 
 --> Running transaction check
 --> Processing Dependency: libt1.so.5 for package: php-gd
 --> Finished Dependency Resolution
 Error: Missing Dependency: libt1.so.5 is needed by package php-gd
 
 I have searched on google and none of the solutions seem to work.  Does 
 anyone have any ideas?
 
 Terry