segfaults with apt-get update

[Nigel Henry]

Sorry about this. This I think is the first time ever I'd had a problem with 
apt.

tried to open synaptic as root, and it opened, and about 3 secs later crashed.

then tried an apt-get update, which normally takes about 30 mins on dialup. It 
got as far as the core/updates/5/i386/ filelists.xml , which is the last to 
be dl'd. I don't know how far it got, but then saw a newline.
Segmentation faultsts... 0%

There was an update for apt on 26 Nov, but I have run apt-get update, and got 
further updates 2 times after the update to apt.

Is it likely that I need to rebuild the rpmdb, and if so, would someone kindly 
give me the necessary incantations to run on the command line.

Thanks.

Nigel.