Okay I think I know what your problem is. You haven't given much information such as how the permissions are screwed up but based on what you've said so far and my knowledge of windows and ISCSI I'm going to use my imagination.
ISCSI isn't a typical share such as CIFS or NFS. An ISCSI target it presented to the initiator as raw storage that must be formatted. The computer initiating the connection treats that storage space as it's own internally connected device. Are your computers on a domain? If they're not on a domain then chances are computer one initiated the connection, formatted the drive and applied permissions. Computer 2 initiated the connection, detected a NTFS.. or FAT for some weird reason file system and mounted the drive. Now, computer two sees a "administrator" user (just an example) on a folder or file but this user is from computer one. Although they share the same name this user is not the same as the administrator account on computer two. The identifier for the administrator account on both computers are different so they are not the same user. In some scenarios this is no big deal and doesn't matter but there are other scenarios where you'll get a big fat access denied because Windows isn't looking at the name of the account but the identifier. With the little information you provided I'm willing to bet that this is where your problem is.
Some windows versions support multi path... I think that's what it's called. That allows you to connect a single ISCSI target to multiple initiators. It avoids data corruption but I'm not sure it helps with permissions. That's another issue with what you're doing. You really have to watch out for data corruption. Remember, each initiator is treating that ISCSI target as it's very own. What you're doing is like connecting a sata drive to 5 different computers at the same time. As I know it with out multi path you're destine to corrupt some data.
Personally, I've never trusted multi path (or what ever it's called), but to be honest I've never used it... it just doesn't seem like a good idea to me. If I were you I would give each machine it's own ISCSI target or setup a CIFS or NFS share. If you have to do ISCI give each it's own target and setup a 3rd party replication of some kind to keep the different targets synchronized (if that's needed). Depending on your Windows versions replication is built in and would be more than helpful in keeping the targets synced.
Hope this helps, if not lets get a little more information. If I were you I'd read up a little more on ISCSI and how it works (not that I'm an expert).
