[CentOS] Problem upgrading CentOS 4.4 installation

Hi all,

I'm trying to upgrade a Dell Inspiron 5000e laptop with CentOS 4.4 installed.
When dependencies is checked I receive error "Cannot unmount CD
/mnt/sources...". I have CD media and I have tried both text and graphical
installer.

Anyone have a clue ? Maybe the spec for this laptop is to weak and I must
stick with my 4.4 installation... 700Mhz 512Mb ram.

When I use the graphical installer, the X server starts but does not
display  correctly. It is possible to use but you have to guess what and
where to click sometimes.

     Jens