Sharing OS between users

Yesterday the main computer died, and installed the backup onto the "backup computer".
Previously both users could run the same version of parallels at a time... Now it is no longer the case.

The volume that the parallels is on is an encrypted 25GB volume that is in /users/shared as Nu_Windows.dmg
Only one user is on the machine at a time, and the volume is mounted as a startup item in OS X.
From the Jo account it works just fine.
From the Heather account I get the following error when I click on the winxp.pvs in (Volumes/)Nu_Windows/winxp:
Unable to lock out the configuration file /Volumes/Nu_Windows/winxp/winxp.pvs

Then when I click "OK" I get:
Virtual machine cannot be started because of the following problem:
Unable to get the geometry of the virtual hard disk.
Perhaps file /Volumes/Nu_Windows/winxp/winxp.hdd is not a valid virtual hard disk image file.

When I try and "Import" from a "Virtual Disk Image" I get:
"Unknown error occured while Parallels Transported was collecting he information about the selected disk image.
Make sure that: the disk image is not a read-only file; you have permission for this sile; the file is not used by other application."

For both users I have Parallels set to use the "Default folder for virtual machines:" (in the preferences) set to /Volumes/Nu_Windows/winxp

I have looked at the permission using "get Info" and they looked OK.
Here are the permissions as seen from the affected users account using a terminal:

Jomac6:winxp Heather$ cd /Users/Shared/
Jomac6:Shared Heather$ pwd
/Users/Shared
Jomac6:Shared Heather$ ls -lstar
total 52429120
0 -rw-r--r-- 1 root wheel 0 31 May 2008 .localized
0 drwxr-xr-x 18 jomac5_admin wheel 612 3 Dec 22:12 Capture1
0 drwxr-xr-x@ 3 Jo staff 102 8 Dec 23:21 CanoScan LiDE 500F
0 drwxrwxrwx@ 2 root wheel 68 7 Feb 16:36 SC Info
0 drwxr-xr-x 6 Jo wheel 204 8 Feb 23:35 Crap
0 drwxrwxrwt 9 root wheel 306 8 Feb 23:53 .
16 -rw-rw-rw-@ 1 jomac5_admin wheel 6148 8 Feb 23:53 .DS_Store
0 drwxr-xr-x 12 root admin 408 9 Feb 09:10 ..
52429104 -rw-rw-rw-@ 1 Jo wheel 26843701248 9 Feb 15:27 Nu_Windows.dmg
Jomac6:Shared Heather$


Jomac6:winxp Heather$ pwd ../
/Volumes/Nu_Windows/winxp
Jomac6:winxp Heather$ ls -lstar ../
total 2920
2880 -rw-rw-rw- 1 Heather Heather 1474560 20 Jan 2008 unattended.fdd
0 drwxrwxrwx 12 Heather Heather 408 2 Feb 2008 ASPACS Templates
0 drwxrwxrwx 14 Heather Heather 476 3 Feb 2008 Assessment & Treatment Interventions
0 drwxrwxrwx@ 6 Heather Heather 204 4 Feb 2008 Burn Folder.fpbf
0 -rwxrwxrwx 1 Heather Heather 0 7 Dec 03:01 .com.apple.timemachine.supported
8 -rwxrwxrwx 1 Heather Heather 15 7 Feb 19:30 .winxp.pvs.lock
0 drwxrwxrwx 14 Heather Heather 544 7 Feb 22:47 .
32 -rwxrwxrwx@ 1 Heather Heather 12292 9 Feb 08:50 .DS_Store
0 drwxrwxrwx 6 Heather Heather 204 9 Feb 09:04 winxp
0 drwxrwxrwx 15 Heather Heather 510 9 Feb 09:10 .fseventsd
0 drwxrwxrwx@ 2 Heather Heather 68 9 Feb 15:27 .Trashes
0 drwxrwxrwt@ 4 root admin 136 9 Feb 15:27 ..
Jomac6:winxp Heather$ ls -lstar
total 23597168
16 -rw-rw-rw-@ 1 Heather Heather 6148 7 Feb 21:10 .DS_Store
0 drwxrwxrwx 14 Heather Heather 544 7 Feb 22:47 ..
0 drwxrwxrwx 129 Heather Heather 4386 8 Feb 18:40 Windows Applications
8 -rw-rw-rw- 1 Heather Heather 3388 9 Feb 09:03 winxp.pvs
23597144 -rw-rw-rw- 1 Heather Heather 12081736192 9 Feb 09:04 winxp.hdd
0 drwxrwxrwx 6 Heather Heather 204 9 Feb 09:04 .
Jomac6:winxp Heather$

This was working previous the main computers HDD failing yesterday, so I know that it can be done... Just can't figure out how.
Any thoughts would be appreciated

 

Delete this file
8 -rwxrwxrwx 1 Heather Heather 15 7 Feb 19:30 .winxp.pvs.lock
also please put here ls -Rla

 

fixed

Did that... also in the middle of the posting I went back and closed the encrypted volume where the OS is at.
The permissions before opening was
Jo rw-r--r-- Nu_Windows.dmg
I changed that to:
Jo rw-rw-rw- Nu_Windows.dmg

I think that may have been the key.
Even though the internal permissions looked OK, the .dmg may have been an issue.
Maybe the sleep followed by coffee helped.

Thanks!
It is all working brilliantly now.