automount fails to detect the cd. cannot read from cd-r/rw drive

i have dual boot p3 850mhz/320mb ram/2 hardisk(80+20gb) pc. i use windows xp. this is my first experince with linux. i have installed ubuntu 7.04.

my cd-r/rw drive behaves funnily. it is unable to read my cd. if i insert my cd, the drive will hum but i cannot read my data(irrespective of the format). however,after inserting my cd if i restart my pc or if i insert my cd at the time of booting then it is perfectly read by my drive. but as soon as i eject my cd-r/rw drive and insert another cd or re-insert the same cd the drive fails to read the cd. the drive works perfectly under windows. i use smsung cd-r/rw 252F

using google i have been able to do the following commands:

mahesh@mahesh:~$ ls -l /dev/cdrom
lrwxrwxrwx 1 root root 4 2007-05-23 16:26 /dev/cdrom -> scd0

mahesh@mahesh:~$ sudo mount /dev/scd0 /media/cdrom0
mount: No medium found

mahesh@mahesh:~$ sudo mount /dev/cdrom /media/cdrom0
mount: No medium found

mahesh@mahesh:~$ sudo mount /dev/hdb /media/cdrom0
mount: special device /dev/hdb does not exist

the contents of my /etc/fstab/ file are:

# /etc/fstab: static file system information.

#

# <file system> <mount point> <type> <options> <dump> <pass>

proc /proc proc defaults 0 0

# /dev/sdb1

UUID=683d08e8-3c07-4a7d-93a7-7843b74d5e3f / ext3 defaults,errors=remount-ro 0 1

# /dev/sdb5

UUID=944af908-e7e3-4aea-b454-6f424e358394 none swap sw 0 0

/dev/scd0 /media/cdrom0 udf,iso9660 user,noauto 0 0

/dev/fd0 /media/floppy0 auto rw,user,noauto 0 0

the contens of my /etc/fstab.pre-uuid/ are:

# UNCONFIGURED FSTAB FOR BASE SYSTEM

the contents of my /usr/share/ubuntu-docs/ubuntu/sample/fstab_automountfs/ are:
# /etc/fstab: static file system information.

#

# <file system> <mount point> <type> <options> <dump> <pass>

proc /proc proc defaults 0 0

/dev/hda2 / ext3 defaults,errors=remount-ro 0 1

/dev/hda5 none swap sw 0 0

/dev/hdb /media/cdrom0 udf,iso9660 ro,user,noauto 0 0

/dev/fd0 /media/floppy0 auto rw,user,noauto 0 0

/dev/hda1 /media/windows ntfs umask=0222 0 0

the contents of my /usr/share/ubuntu-docs/ubuntu/sample/fstab_automountnetworkfolders/ are:

# /etc/fstab: static file system information.

#

# <file system> <mount point> <type> <options> <dump> <pass>

proc /proc proc defaults 0 0

/dev/hda2 / ext3 defaults,errors=remount-ro 0 1

/dev/hda5 none swap sw 0 0

/dev/hdb /media/cdrom0 udf,iso9660 ro,user,noauto 0 0

/dev/fd0 /media/floppy0 auto rw,user,noauto 0 0

//192.168.0.1/linux /media/sharename smbfs credentials=/root/.smbcredentials 0 0

the contents of my /usr/share/ubuntu-docs/ubuntu/sample/fstab_automountnetworkfoldersall/ are:

# /etc/fstab: static file system information.

#

# <file system> <mount point> <type> <options> <dump> <pass>

proc /proc proc defaults 0 0

/dev/hda2 / ext3 defaults,errors=remount-ro 0 1

/dev/hda5 none swap sw 0 0

/dev/hdb /media/cdrom0 udf,iso9660 ro,user,noauto 0 0

/dev/fd0 /media/floppy0 auto rw,user,noauto 0 0

//192.168.0.1/linux /media/sharename smbfs credentials=/root/.smbcredentials,dmask=777,fmask=777 0 0

the contents of my /usr/share/ubuntu-docs/ubuntu/sample/fstab_automountfat/ are:

# /etc/fstab: static file system information.

#

# <file system> <mount point> <type> <options> <dump> <pass>

proc /proc proc defaults 0 0

/dev/hda2 / ext3 defaults,errors=remount-ro 0 1

/dev/hda5 none swap sw 0 0

/dev/hdb /media/cdrom0 udf,iso9660 ro,user,noauto 0 0

/dev/fd0 /media/floppy0 auto rw,user,noauto 0 0

/dev/hda1 /media/windows vfat umask=000 0 0

i have got all these files after searching “fstab” in the “file system”.

Please note that /dev/hdb does not exist on the system. I was not able to find it throug search or going to /dev through nautilus even after pressing ctrl+h(show hidden files).The only devices mentioned in the directory were:
/dev/cdrom
/dev/cdrw
/dev/scd0

the other typical thing I found was that if we type computer:/// in the file browser i can see all the drives including cd-rw drive. on right clicking on cd-rw drive and going through its properties/permissions/ I found the following:
 owner: unknown
access:read only
group:unknwn
access:read only
others:unknown
access:read only
execute:unchecked
selinux:unknown
last changed:unknown

any changes i tried to effect by using my mouse gave an error message “permission cannot be changed”.

on going through properties/drive i found out:

vendor: samsung
model:cd r/rw 252F
serial:<blank>
firmware:R804
connection:SCSI
media:cd-rw drive
removeable:Yes(ejectable)
external:no

settings:
mount point:<blank>
file system:<blank>
mount options:<blank>
should i make any changes here.? if any changes are to be made then how?

i typed the following:

mahesh@mahesh:gksudo nautilus

but on typing computer:/// the only drive i could access was file system .

what do i do next?