Centos 5.2 yum install issues

Centos 5.2 yum install issues

I've been running into this error lately whenever using yum on a centOS
5.2 machine. Whenever I try installing anything I get dependency errors
and yum tells me to try using package-cleanup. I do, but it dosen't do
anything, nor does --skip-broken.
for instance, when I try install postgresql90-server, I get these errors
at the end of the yum install:
--> Finished Dependency Resolution
postgresql84-8.4.9-1.el5_7.1.x86_64 from os has depsolving problems
--> postgresql84 conflicts with postgresql90
postgresql84-server-8.4.9-1.el5_7.1.x86_64 from os has depsolving problems
--> postgresql84-server conflicts with postgresql90-server
Error: postgresql84 conflicts with postgresql90
Error: postgresql84-server conflicts with postgresql90-server
You could try using --skip-broken to work around the problem
You could try running: package-cleanup --problems
package-cleanup --dupes
rpm -Va --nofiles --nodigest
Is there anyway to get rid of these dependency errors? I googled it, and
tried every solution I've found but nothing is helping me remove these
errors.