Losing some edited contents in Impress after saved as pptx file.

I try to modify a pptx file with Impress of LibreOffice under 64-bit Linux.

I used LO built-in clipart in it. After I saved the file then open the file again.

some of these clipart disappeared.

I edited the pptx file again and saved as odp file,

these content are kept as opened in LO Impress and It is OK to use.

But, when I try to open the above odp file under windows 7 MS PowerPoint 2010,

It reports the file as corrupted.

After PowerPoint “fixes” the above odp file, all content disappeared. ( It’s OK though: I already backed up.)

Can anyone help me?

Thanks a lot.

Ok, finally I saved the file as ppt file then it works ok now…