Drawing Access Violations and corrupted files

[reginamariaaia360200]

I am doing an architectural project on AutoCad LT 2007/Windows XP, and working with others in the office who are working on AutoCAD 2009/Windows 7. We have started having "ghost in the machine" issues right about the time the project is due for a deadline (of course). Here are some of the symptoms:

1. ACAD 2009 user: each time he opens a sheet file that has x-references, it does not automatically load the title block and the xref plan. He gets the bubble that the drawing "may have changed". We are both set to demand load with copy, although I cannot find any setting or system variable that would keep a file from automatically loading the xrefs when opening the file.
2. If I (LT 2007)open a sheet file and work in it, then save and close it, my colleague cannot open the drawing any more. He gets notification that the drawing is in use, would he like to open "read only"...but it doesn't allow us to open read only. If he continues to try to access the drawings he gets the warning "Access Violation. Unable to open drawing."
3. If I select this now corrupt file in Windows Explorer, Explorer locks up and becomes non-responsive. If I try to select it from LT2007, the program seizes. The drawing cannot be selected to recover. We have been restoring the backup files with a new name. In trying to save over the original file, it will not allow it because it is in use.
4. My colleague can access the file from Windows Explorer (Windows 7) to select and delete, but even when the file is deleted we cannot rename ore save as the original name because we get the same access violation.
5. We have audited, purged, re-audited and re-purged all of the sheet files, and this continues to happen willy nilly to different files. This week it happened to one file, I asked our IT guy to delete it from the server. The next day he had not deleted it, and we could both open it...but a different file had the problem.

Can anyone help? I fear this is a problem because of the interface between 2009/Windows 7 and LT2007/XP. It also concerns me that some objects in the project files were imported from ArchiCAD (which I believe is evil). I realize it is more likely the former.

Thanks all - this is my first post!

Regina

Update: If we both reboot, it seems to solve the problem. And if it makes a difference, we are on a Novell network.