I just changed motherboards, and my old Mobo had an on-board AIC-7880 SCSI controller, the new one had a 7890. Kudzu detected the difference and popped up asking me whether I wanted to remove my 7880. At this point I was cautious so I said "do nothing". Then it asked me if I wanted to configure my 7890 and I said ok and boot continued. Next reboot it popped up again asking if I wanted to remove the 7880 so I said yes... now it "hung". After a minute or so I rebooted and the system came up... I'm not 100% sure now, but I think it asked me if I wanted the skip the hardware detection? Anyway, I looked in the /etc/sysconfig/hwconf file and both the 7880 and 7890 were listed. So I ran kudzu manually and it hung. "top" showed that it was using rapidly increasing amounts of memory... after about 30 seconds it had grown to 500MB (I have 256MB RAM and a gig of swap). I killed kudzu, manually removed the 7880 from /etc/sysconfig/hwconf and re-ran it and it seemed fine.
Ooh, that's not good. Will try and duplicate it here.
This is fixed iwth the kudzu currently in raw hide.