I only have one version of Office on this computer and it has only had this one version of Office 2010. Excel is working perfectly fine, with PowerPoint open or not. It is only when I am working on a Excel worksheet from within PowerPoint.
This problems is very difficult to debug as the problem is very intermittent. It might show up within minutes of rebooting and opening PowerPoint or it may not manifest itself for a couple of days. For example, I have had a PowerPoint open for two days
now with the problem not showing up, I have worked on the file on and off for a couple of days. But when I went to save the file just now, one of the four excel tables had gone bad. There may be some relationship to the problem showing up when a save is
started, or more likely, perhaps it is just that when I try to save, the Save feature is catching that one of the tables is bad and won't let it save. Note that it says it is read-only and you can no longer save (or "save as") the file. It claims the file
is now read-only and requires you to save as a different named file. Which you can do if all the worksheets are fixed (by cut and pastes as described above). But if you have them on multiple pages, you can't fix them all fast enough. Usually they go bad
as fast as you try to fix them. Now, lest you think it is always caused by saving, saving is not the only reason the problem shows up. It sometimes shows up without a save taking place at all. I have frequently made saves without the problem showing up.
For example, now that I have fixed and saved the file under a new name the tables are all OK and I can save just fine without it However, once any table has gone bad you can't save it, even if you cut/paste and fix the tables. You can save as, but you can't
save. So there is some relationship.
Additionally, I would note that once one table goes bad, then a chain reaction seems to start (with no perceivable pattern or order or timing). All the other tables go bad in reasonably short order (in several minutes).
Additionally, I have conducted a clean boot (which was recommended on some similar problems) but that didn't stop the problem.
Additionally, I have a new hint which is that I have found a relationship to tables on multiple pages. The file that I worked on for two days only had tables on a single page. But when I put a table on a second page then the problem started. But not
with the second page table, but with one of the tables on the first page. To test, I just created a new file and can pretty reliably cause the corruption to take place with the first page as soon as I put a table on the second page.
Additionally, I discovered by a serendipitous slip of the mouse, that the problem will occur if I add any type of table: EXCEL, or DRAW TABLE or regular PowerPoint Table. But interestingly only the EXCEL file will become uneditable. The draw and normal
powerpoint tables will continue to be editable. Only the EXCEL table is bad. But the cause can be any type of table. Ok. Further research is indicating that if I add a chart or a shape or ANYTHING to the second page it fires off the excel file to go
bad. But it seems to be tied to the INSERT tab. If I put a shape on the second page via the HOME tab then it doesn't cause the problem. If normally add things from the Quick Access Toolbar (shapes, text, etc.). And if you add text or a shape that way,
you never see the problem. It is only when you use the INSERT tab. And again the effect is only to corrupt the excel tables not anything else. You can still edit the shapes or other tables. And it only happens when you INSERT the thing on a different page
from the excel table. For example, if you insert a screenshot on the same page as the excel table it won't affect it. But if you insert the same screen shot on a second page then the first pages excel file will immediately go bad. You can leave the object
on the second page and cut and past the first pages excel file and it will "heal" but after a while the problem will come back.
Ok, further testing has destroyed by theory that you can insert things in other ways and it won't cause a problem. I just had a new file with an excel on the first page. I went to the second page and entered in some text via the quick access tool bar
and it made the first page excel file go bad. But this is confusing as it was most definitively not doing it before.
Anyway. . . I will continue to test. I appreciate any help. This is ruining my job.