Error When Sharing Excel Spreadsheet On Vista Peer-To-Peer Network

I've just upgraded a small business from Win XP and Office 2000 to Vista and
Office 2007. They have three Vista machines (a Home Premium laptop and two
Vista Ultimate PCs) networked peer-to-peer with a shared folder on one of the
PCs containing various Word documents, Excel spreadsheets, etc.

When the user on the PC with the shared folder has a spreadsheet open and
the user on the other PC tries to open it, Excel locks up and they get the
following Vista error:

Description:
A problem caused this program to stop interacting with Windows.

Problem signature:
Problem Event Name: AppHangB1
Application Name: EXCEL.EXE
Application Version: 12.0.6024.5000
Application Timestamp: 465f21c3
Hang Signature: c776
Hang Type: 0
OS Version: 6.0.6000.2.0.0.256.1
Locale ID: 2057
Additional Hang Signature 1: 65dc5429230d5a9288797c8f600c1be6
Additional Hang Signature 2: b826
Additional Hang Signature 3: 2c8741727759f200a8742beb442a973f
Additional Hang Signature 4: c776
Additional Hang Signature 5: 65dc5429230d5a9288797c8f600c1be6
Additional Hang Signature 6: b826
Additional Hang Signature 7: 2c8741727759f200a8742beb442a973f

The second user is trying to open the spreadsheet to view it, rather than
make any changes, and this used to work perfectly on their old machines.


For info, this works perfectly well the other way round, i.e. if the user on
the PC without the share opens a spreadsheet first and then the user on the
computer with the share opens the same spreadsheet there isn't a problem.

Can anyone advise?

I have also posted this problem in the Excel discussion group as I'm unsure
exactly where the problem lies.