Having just re-partitioned my hard drive with the help of the forums here, my df command now shows the wrong information as below:
Filesystem Size Used Avail Use% Mounted on
/dev/ide/host0/bus0/target0/lun0/part1
738M 660M 78M 90% /
/dev/ide/host0/bus0/target0/lun0/part5
25G 9.0G 16G 37% /home
/dev/ide/host0/bus0/target0/lun0/part6
8.8G 3.0G 5.9G 34% /usr

The problem is that me 1st partition is 3.9G, not as shown, 738M.
What is the best way to proceed to get this to be read correctly.

TIA

Depending on how you repartitioned your hard drive, did you remember to update your fstab file? (some tools do this for you) The only time I've seen the problem you mention was on RH 7.2 where rebooting fixed the problem. If df is broken, does du show the proper partitions? Sorry I can't be much help......

Used mandys diskdrake to do the partitioning. But this is even stranger. Check the partition with cfdisk, shows /dev/hda1 as 3.65Gb, whereas df only shows the 738Mb.
Diskdrake shows the partition size correctly, qtparted does as well. But even in Knoppix, the df command only shows 738Mb, but its own qtparted shows 3.65Gb.
I have run reiserfsck and it returns zero errors. WTF is going on I don't know.
This is really very strange!
New info today, (3rd June)
Booted box of the Mandy DVD and went into rescue mode.
lsparts shows /dev/hda1 as 3.65Gb, df shows as 738Mb. This is increasingly looking like a re-install of the system. Anyone any ideas?

Solved,
Used live CD pclinux2k4, then ran the command resize_reiserfs on /dev/hda1. Everything now back to normal.