I mounting some iso’s via fstab, with the following commands.

# ISO mount in fstab - used for PXE Booting.
/Apps/WinXP(SP3).iso /srv/pxeboot/images/winxp/ udf,iso9660 user,auto,loop 0 0
/Apps/Windows7.iso /srv/pxeboot/images/win7/ udf,iso9660 user,auto,loop 0 0
/ Apps /win7thin.iso /srv/pxeboot/images/win7thin/ udf,iso9660 user,auto,loop 0 0
/ Apps /Windows.8.1.iso /srv/pxeboot/images/win8.1/ udf,iso9660 user,auto,loop 0 0
/ Apps /Ubuntu13.10.iso /srv/pxeboot/images/ubuntu/ udf,iso9660 user,auto,loop 0 0
/ Apps /knoppix7.2.iso /srv/pxeboot/images/knoppix/ udf,iso9660 user,auto,loop 0 0

This works as expected and the each of the iso are mounted properly.
I have two problems which are related.
1) if I perform a sudo fuser -m /dev/loop1 on each of the mounts, the systems tells me that each of the following process has the device open. by the way ,the same process are listed for all mounts. I also can’t un-mount the device unless I use the –L option.

/dev/loop5: 1 243m 322 392 396 878 892 1028 1222 1225 1232 1236 1238 1239 1240 1243 1245 1256m 1287 1289 1330 1331 1332 1334 1360 1363 1398 1399 1418 1420 1425 1430 1435 1445 1456 1461 1462 1465 1472 1488 1491 1492 1493 1494 1499 1512 1519 1542 1603 1728 1732 1816m 2055 2161 2456 2507 2516 2679 2898 3052 3054 3373 3544 3571 3572 3896 4005 4117 4172 4173 4174 4175 4176 4478 4494 5027 5065 5245 7032 7156 7273 7274 8013 9556 9771

2) The above would not be issues, however when I try to boot some (especially Ubuntu) of the iso's. the boot process hangs.

If I mount each of the iso manually, everything works fine.

Any ideas?