[Oberon] Trap in storing a FAT file.

[Peter Easthope]

On one pc there is a trap in half of all attempts to
store a FAT file.  I've never used a trap report to chase 
down a bug and can use a little guidance.  Can anyone
tell me where to begin with analysing this report.

Thanks,           Peter E.

TRAP -14  NIL reference ( 00000000H ) (PC Native 05.01.2003)
OFSFATVolumes.AssignDirectoryEntry  PC = 22443
c =  00000000H
dc =  00000000H
direntry =  00000010H
dummy = 0
num = 0
p =  003976E0H
pos = 0
res = 0
vol =  001B5700H
OFSFATVolumes.WriteDirectoryEntry  PC = 24169
@dim = 2048
chksum =  00000000X
cluster = 0
d = 0
dirCache =  00000000H
direntry =  00000010H
dummy = 0
idx = 0
k = 0
n = 0
pos = 0
res = 0
t = 0
unicode = 47, 75, 69, 82, 77, 73, 84, 47 ...
vol =  001B5700H
OFSFATFiles.Rename  PC = 2781
d = 52958
f =  0033FF40H
fn = "MAILIN.Bak"
fs =  00307140H
i = 18
new = "/KERMIT/MAILIN.Bak"
newf =  00000000H
newpath = "/KERMIT/"
old = "/KERMIT/MAILIN"
oldpath = "/KERMIT/"
rep =  00000000H
res = 0
t = 40114
OFS.Rename  PC = 4688
fnew = "/KERMIT/MAILIN.Bak"
fold = "/KERMIT/MAILIN"
new = "C:/KERMIT/MAILIN.Bak"
nfs =  00307140H
ofs =  00307140H
old = "C:/KERMIT/MAILIN"
pnew = "C"
pold = "C"
res = 0
Files.Rename  PC = 2024
new = "C:/KERMIT/MAILIN.Bak"
old = "C:/KERMIT/MAILIN"
res = 0
ET.RenameOld  PC = 14016
bck = "C:/KERMIT/MAILIN.Bak"
i = 20
name = "C:/KERMIT/MAILIN"
res = 0
ET.store  PC = 14672
R =  00000034H
S =  00000030H
V =  00000000H
ch =  00000000X
f =  00000000H
len = 0
par =  0018FC60H
r =  00000028H
tF =  0039F320H
typ = a
ET.StoreAscii  PC = 15089
Oberon.Call  PC = 4860
Mod =  00067240H
P = ET.StoreAscii  PC = 15079
i = 3
j = 13
name = "StoreAscii"
new = FALSE
par =  0018FC60H
res = 1
TextFrames.CallCmd  PC = 12027
F =  00345960H
cmd = "ET.StoreAscii"
new = FALSE
par =  0018FC60H
pos = 80
res = 1
TextFrames.Call  PC = 12915
F =  00345960H
S =  00000048H
h = 0
hint = "ET.tem."
i = -1
new = FALSE
pos = 69
TextFrames.Edit  PC = 20137
F =  00345960H
Keys = {1}
M =  00000060H
R =  0000004CH
X = 404
Y = 591
beg = 0
buf =  00000000H
ch =  00000000X
end = 0
keysum = {1}
pos = 69
text =  00000000H
time = 0
TextFrames.Handle  PC = 21222
F =  00345960H
F1 =  00000000H
M =  00000020H
ET.Handle  PC = 10006
F =  00345960H
M =  0000000CH
T =  0016B1C0H
handled = FALSE
ml = FALSE
tF =  00345960H
MenuViewers.Handle  PC = 4432
M =  00000014H
Main =  0039F320H
Menu =  00345960H
V =  000770C0H
V1 =  00000000H
Oberon.Loop  PC = 8578
M =  00000010H
N =  0000000CH
V =  000770C0H
X = 404
Y = 591
ch =  00000000X
keys = {1}
oldshift = {}
shift = {}
System.Init  PC = 20212
F =  00369200H
S =  00000044H
T =  00369180H
Wt =  00000050H
ok = TRUE
OFSBoot.Call  PC = 426
c = System.Init  PC = 19688
cmd = "Init"
i = 11
j = 4
m =  001633E0H
protect = TRUE
OFSBoot.BootSystem  PC = 2780
s = "System.Init"
OFSBoot.$$  PC = 13
@SELF =  0003F480H
SELF =  0003F480H