IIGS won't handle floppies

[gospodin@indigo.ie (Vincent Quinn)]

No sooner have I got one problem fixed (//c RAM) than a different one
crops up. So I'm looking for help again!

When booted from a hard disk, my IIGS has decided it's not going to read,
format or write to any sort of floppy disk attached to the SmartPort. SCSI
read/writes to hard disk or Zip are fine.

If I boot the GS from a 3.5" floppy it appears to be fine and reads the
disk with no problem - it won't format a 3.5" disk though. 

I'd love to find out that this is a software problem, but I suspect it
must be hardware (SmartPort controller chip?). For the past six months I
have had one Apple 3.5" and two converted Disk ][s daisy-chained to the
port with no problems. Recently I added a second 3.5" - that could be
purely co-incidental.

Anyway, when booting from a hard disk, the symptoms are:

�plug in one converted Disk ][ and boot up - the machine sees two of 'em
�put a 3.5" disk in either drive and everything locks up - the busy light
on the drive stays on until a forced restart
�a 5.25" disk will mount on the desktop - but if I try to format it I get
"I/O error $27".

All of the four drives seem fine. The 3.5"s work perfectly
(read/write/format) when attached to my PC Transporter (in the same GS).
The Disk ][s work perfectly (read/write/format), again with the same GS,
if attached to a Disk ][ controller card in either slot 6 or slot 2. They
are also fine attached to a //c disk port.

I've tried booting from a different hard disk (different system) and from
a Zip partition  (same system) and had the same problems with the floppy
drives.

My last (forlorn?) hope that it could be software is - I'm getting a
message I've never seen before when trying to launch some apps on the hard
disk by double-clicking:
Error: could not load/unload resource
Type=8001
ID=00005A06
Error=1E06

Also (this may be completely unrelated), if I try to open 'Control Panels'
from the Apple menu, usually nothing happens - I have to use
<Apple><control><escape>.

Anyone tell me what's wrong? If it's hardware, I have a scrapped //c
motherboard - can I replace a faulty GS chip with anything on there (all
of the //c chips except for the IWM are fine)?

Alternatively, (since I have a work-around for the 5.25"s), can I leave
the 3.5" drives attached to the PC Transporter and access them when in
GSOS/ProDos - perhaps by patching ProDos? Would they then format disks
under MFM, instead of GCR?

Finally, if I were to invest in a BlueDisk controller and MFM floppy
drive(s), could I use them to access/boot from my Apple II 3.5" GCR disks?

TIA

Vincent Quinn

(I'd appreciate e-mail copies of any posts, just in case I miss 'em)