It would be much easier to diagnose the problem with the .pptx file because the .pptx file uses XML which can be read. The .ppt file is binary which appears as gibberish. If possible upload the .pptx file to a file share site or Google Drive or Dropbox etc.
Neither AOO nor LO open the file properly and there does appear to be corruption in the file. When I highlight the overwritten stuff and move it I get a brief sight of these rectangles suggesting some underlying structure in the selected material.
I can select the underlying rectangles and move them. They appear to be some sort of rectangle with text in them.
It may be a new feature of PowerPoint which neither AOO nor LO supports. See
[Tutorial] Differences between Writer and MS Word files for a discussion.
Have you tried the free PowerPoint on line? See
View a presentation without PowerPoint for a link.
A new way to view presentations
PowerPoint Online is a free alternative that provide some of the same benefits of PowerPoint Viewer and can display some newer features (such as the Morph feature and animations added to PowerPoint after version 2010).
If you have a Microsoft account (hotmail.com, outlook.com, live.com, msn.com) or an Office 365 work or school account, you can view and edit a presentation for free in a web browser by saving the file to OneDrive or Dropbox and using PowerPoint Online to open it.
As an aside it is complete arrogance for a company to send you a .pptx file assuming you have PowerPoint. If I remember correctly, PowerPoint can save presentations as an executable file which anyone can run without needing PowerPoint.