I'm having trouble saving my PowerPoint slideshow on Office 2008 running Mac OS X Lion. Any idea why?

Hi, I'm running Office 2008 on Mac OS X Lion. I have all of the latest software updates for both my Mac and for Office. However, PowerPoint will not save a slideshow. When I try to save, I'm told there is an "error accessing" where I want to save it. Other times, it says I "do not have permission to save or open." Any idea why this is occurring? I e-mailed a slideshow to myself, and was able to open it on another PC (a Windows OS). I'm not sure if it's because of a recent update. Any help would be appreciated.

Just a quick note, I've looked over all of the posts about Office 2004. But it seems that Office 2008 wasn't affected by any recent or past updates. So, I'm stumped as to why this is happening, and I didn't find anything online about it. Has anyone else experienced this?

Thank you!