Problems with mounting .ISO files

Question

I'm using Precise, with GNOME. I've attempted to install some retro,
multi-cd games (KOTOR1) via .ISO images and WINE,

but I can't get the ISO's to mount correctly. First I tried GMountISO, which showed a read-only warning but worked - until I went to unmount. When the installation program asked for CD 2 I couldn't unmount from the /cdrom folder because neither GMountISO or umount from terminal could detect the mount.

After a reboot, I changed to GISOMount (different somehow, I guess?), but when I attempt to mount the ISO I get an error window explaining the syntax of the mount command and, which is also what I get when I attempt to use mount from terminal. After checking /media from terminal on a lark I see the disc mounted there twice over, but umount won't recognize it, even when I specify the full path sudo umount /media/KOTOR_1.iso. It cleared up upon reboot.

Can someone please assist?

UPDATE :: Thanks for the quick response. What's weird, is the images are like stuck in limbo... I'll show you:

sc@sc-HP-110-3700:/media$ ls
cdrom  KOTOR_1(0)(vcd)  KOTOR_1(vcd)
sc@sc-HP-110-3700:/media$ cd cdrom 
sc@sc-HP-110-3700:/media/cdrom$ ls 
sc@sc-HP-110-3700:/media/cdrom$ cd .. 
sc@sc-HP-110-3700:/media$ umount KOTOR_1(vcd) 
bash: syntax error near unexpected token `(' 
sc@sc-HP-110-3700:/media$ umount KOTOR_1.ISO 
umount: KOTOR_1.ISO is not mounted (according to mtab)
sc@sc-HP-110-3700:/media$ sudo umount -a 
umount: /run/shm: device is busy. 
        (In some cases useful info about processes that use
         the device is found by lsof(8) or fuser(1))
umount: /run: device is busy.
        (In some cases useful info about processes that use
         the device is found by lsof(8) or fuser(1)) 
umount: /dev: device is busy.
        (In some cases useful info about processes that use
         the device is found by lsof(8) or fuser(1)) 
umount: /: device is busy.
        (In some cases useful info about processes that use
         the device is found by lsof(8) or fuser(1))
sc@sc-HP-110-3700:/media$ 

UPDATE 2 :: found another anomaly trying to use fuseiso instead, maybe helpful:

sc@sc-HP-110-3700:~/Downloads/KOTOR$ ls
KOTOR_1.ISO  KOTOR_2.ISO  KOTOR_3.ISO  KOTOR_4.ISO
sc@sc-HP-110-3700:~/Downloads/KOTOR$ fuseiso KOTOR_1.ISO ~/cdrom
fuse: bad mount point `/home/sc/cdrom': No such file or directory
sc@sc-HP-110-3700:~/Downloads/KOTOR$ sudo mkdir /media/cdrom
mkdir: cannot create directory `/media/cdrom': File exists

UPDATE 3 :: tried using fuser -ck /media as a last ditch option, the shell kicked over, but when I ran "ls" on the folder again, the files are still present.

Solution

Um, I don't know what GMountISO is, but I would just do it using command line. Linux does not need any additional tools to mount an ISO file.

To mount:

sudo mkdir /media/cdrom
sudo mount -o loop -t iso9660 file.iso /media/cdrom

To unmount:

sudo umount /media/cdrom

EDIT: to mount without administrator privileges, install fuseiso:

sudo apt-get install fuseiso

Then you can mount:

fuseiso file.iso ~/cdrom

and unmount:

fusermount -u ~/cdrom

without sudo.