humm....battery corrosion really shouldn't be an issue on genuine 4000T's, as they have some flat lithium batteries that hardly leaks.
I have the similar problem when I connect a SCSI hdd onto the mobo SCSI chain, cd-roms and tape-streamers work fine, just not HDD's....odd, isn't it?
Anyway, my 4000T also needs a reboot when powering on from a cold-boot, if I use the onboard ide connector.
I guess the 4000T's are temperamental pieces of computers, eh?