My Red Hat 7.3 system which was working fine until now,
hangs giving the following errors while booting.
a)Updating /etc/fstab failed to open /proc/partitions: No such file or
directory .
b)After this it gives a series of errors indicating files
cannot be created because file system is read-only.
I can login in "single user" mode.Also I checked
the /proc directory does have a "partitions" entry.
How should i debug further..
Thanks in advance for any help.

How does your /etc/fstab look like?

LABEL=/ / ext3 defaults 1 2
none /dev/pts devpts gid=5,mode=620 0 0
none /proc proc defaults 0 0
none /dev/shm tmpfs defaults 0 0
/dev/hda4 swap swap defaults 0 0
/dev/cdrom /mnt/cdrom iso9660
oauto,owner,kudzu,ro 0 0
/dev/fd0 /mnt/floppy auto noauto,owner,kudzu 0 0
/dev/fd1 /mnt/floppy1 auto noauto,owner,kudzu 0 0

The last of ext3 values were 1 1 I changed them to 1 2
but no change in the status

I'd change the first line to the partition it really is, something like
/dev/hda5 / ext3 defaults 1 1
Change the '/dev/hda5' with the right entry for your '/' partition. Use fdisk if unsure.

Just today I had a similar error... upon trying to restart apache, I got an error message saying it was unable to create a log file because the fle system was read-only. It turns out the entire partition had been made read-only. dmesg showed that there had been some kind of hardware error writing to the disk (I currently don't have access to the exact text) and so that device was switched to read-only mode. If anyone has any ideas on how to persue this I'd love to hear them. Otherwise I'll plod along as best I can and post any progress I make.

-Edward

Boot from a boot disk or from installation cd (in 'rescue' mode). Run fsck on a partition there's the problem with. It should detect the error (and try to fix it).