I have installed Ubuntu once and because I wanted to upgrade Firefox to 2.0.0.5 (During that time) and messed up the system, I re-install from scratch. Now, although I could see my 2 Windows Parition (FAT 32 for both , 1 for system, the other for personal) , it also shown on Desktop. This was not the one I used to see Ubuntu in the first installation. (I see 2 HDD logo on Ubuntu now, last time I see nothing, perfectly clean on Desktop Ubuntu but 2 Windows Parition is available for me to read/write.) Futhermore, last time I could use CD-ROM drive (52X) open and close as and when I like (With mounting, of course.) , Now, I need to log off before I could un-mount the CD-ROM and take out my CD. What should I set and do before I get back the settings similar to my first experience. (No, because of limited hard disk space, with a total of 20G and without thumb drive or a CD-Writer, I did not backup anything.)

Did you close the application that used your cd-rom?
It is not necessary to log off.
Open a terminal session as root and you can umount the device from the commandline: umount /dev/cdrom

Sorry , I dun understand what you meant by turn off the application? That CD I meant was a VCD, not any installer etc. Anyway , the unmounting through command was useful. However, if I use other account (non root) can add sudo ( sudo umount /dev/cdrom ) without the brackets? Furthermore, last time I could Graphical Unmount, now cannot. Is there a way to graphical unmount because some of my family users really scared of text mode.
Also, asking another question. My Ubuntu Linux could not read .dat files (VCD format) why is this happening even after I installed codecs for Windows in Ubuntu correctly?