error: ip_tables.o init_module:Device or resource busy

I'd like to preface this mail by saying that if a little knowledge is a dangerous thing, then I am very dangerous....

I have recently installed redhat 9.0 and upgraded to iptables 1.2.7a with a 2.4.20-18.9 kernel. When I try to do anything with iptables, I get the following error:-

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e.g. iptables -F
/lib/modules/2.4.20-18.9/kernel/net/ipv4/netfilter/ip_tables.o: init_module: Device or resource busy
Hint: insmod errors can be caused by incorrect module parameters, including invalid IO or IRQ parameters.
You may find more information in syslog or the output from dmesg
/lib/modules/2.4.20-18.9/kernel/net/ipv4/netfilter/ip_tables.o: insmod /lib/modules/2.4.20-18.9/kernel/net/ipv4/netfilter/ip_tables.o failed /lib/modules/2.4.20-18.9/kernel/net/ipv4/netfilter/ip_tables.o: insmod ip_tables failed
iptables v1.2.7a: can't initialize iptables table `filter': iptables who? (do you need to insmod?)
Perhaps iptables or your kernel needs to be upgraded.
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Obviously, there is something wrong with either the kernel or iptables as I have installed it ( using apt-get install, no thanks to redhat). I need to get iptables working yesterday.
Can anyone tell me a no-brainer way to achieve this ?
Does my version of kernel work with this version of iptables ?
Do I have to go back to an earlier version ?
Whats the best way to get out of this mess ?
I remember for my dos days we used to do "format c:" in this kind of situation.

Thanks a lot,

a moron