Save My Sanity - Office 2000

Okay people, I have a problem and a half.

I am running XP Home with two users - myself (Verity) as an Administrator and Jack as Limited. My problem is with my Microsoft Office 2000 Premium suite that I installed.

Everything on my profile works fine. The problem is with Jack's.
He is using Outlook Express 6.
When he receives mail with any of the Office programs (ie word, excel, powerpoint) as an attachment and tries to open them, the following error messages occur, in this order:

Windows cannot find "C:\Documents and Settings\Jack\Local Settings\Temporary Internet Files\Content.IE5FFVMK5L\(attachment name)"
Make sure you typed the name correctly, and try again. To search for a file, click the start button, and then click search.
When you click the OK button the next error appears:

User "Verity" has previously initiated an install for product "Microsoft Office 2000 Premium". That user will need to run that install again before they can use that product. Your current install will now continue.

While this error is on the screen there is another message displayed behind it, which I will detail next. However, if you click OK on the error message above, the Office Premium Gathering Required Information dialogue box appears and then rolls back and uninstalls Office.
However if you click the X to close the error message instead, you are then presented with the hidden message that says:

Error 1705: A previous installation for this product is in progress. You must undo the changes made by that installation to continue. Do you want to undo those changes? Yes No

If you select Yes - the Office Premium Gathering Required Information dialogue box appears and then rolls back and uninstalls Office.
If you select No - the Gathering Required Information dialogue box halts halfway and a blank Office window (depending on the attachment) opens and Office is still installed.

The only way Jack can view any Office attachments is to save them to disk and then open them. However Office has also been known to completely disappear from my system on the odd occasion without either Jack or myself doing anything.

Things I have tried to no avail:

1. I have checked Error 1705 with a Microsoft technician and was told it is a Windows Installer error and the way to get around it was to install the Office suite by bypassing the installer program. I did this (in fact it is the only way I can install it now) but I still get the same errors as detailed.
2. I have tried doing a repair in the Add\Remove programs and in the individual applications themselves. It doesn't repair - it uninstalls.
3. I have tried having Jack as an administrator as well. Nothing changes, the same errors still happen.
4. I tried dragging the Documents and Settings\Jack\Local Settings... folder into the shared documents, as is suggested - it won't allow me to do so.
5. Before reinstalling it for the umpteenth time, I have made sure there are no leftover files, folder or registry entries from the prior installations.

I have been trying to fix this problem for 3 months and am going completely barmy, especially when all seems to be going well (providing the right choices above are made) and out of the blue I switch the PC on and find that Office has disappeared by itself!

Please help