MS Office install corrupting Impress presentations?

I installed MS Office and some diagrams in my existing LibreOffice Impress presentations are corrupted - it appears to be a font problem. Am I being paranoid in suspecting a connection? How can I fix the problem without going into every slide and fixing it by hand?

(Mac OSX 10.7.5, LO, Powerpoint for Mac 2011 14.1)

I found a new folder in /Library named Fonts\ Disabled which had a dozen or so fonts in it, and when I moved them all back to /Library/Fonts and restarted LibreOffice, my slides were fine again. The Fonts\ Disabled folder was created at the same time as a folder /Library/Fonts/Microsoft so I think we know who to blame.

I suppose to switch between Impress and Powerpoint I may have to move the fonts back and forth between Fonts and Fonts\ Disabled. $%#%@! Microsoft!