[CentOS] CentOS 5 Boot Issues

Hi all,

I am still having problems with my desktop system. Having updated it
from 4 to 5, I now have problems with the logs. Neither boot.log nor
dmesg has any data post the update. syslog appears to be normal in that
it starts when it should but does not show any errors. It looks like
whatever is supposed to write to the logs during initial boot is not
doing so, but I am not sure where to look to see what is wrong. 

The other problem I have may or may not be related it is not notifying
me when updates are available although Yum etc appear to be working
correctly.

I have all the data backed up and I could do a fresh install, but I am
trying to avoid this as I would have to spend a lot of time reinstalling
software etc.

Any suggestions?

Thanks Rob