I can only suggest uninstall/reinstall SF again, but using a third-party uninstaller (Revo's Uninstall for instance) which scans for registry leftovers after the uninstall . A standard uninstall leaves behind registry entries that could have caused the problem in the first place.

Otherwise contact Magix tech support

I just tried the revo uninstaller. It seems like it still didn't delete all the leftover files because the registration key still appeared upon reinstall. I have a support request out to magix... We will see how that actually goes.

Any other suggestions? This is incredibly frustrating and is severely delaying my work. Don't know what to do!!!

Have you tried a 'Save As..' in different file formats ? Both standard .wav and .mp3 (with Default Templates) should save without any issue. Maybe try saving to a different hard drive or ext. USB ?
Also in 'Save As' browser window, try un-checking both metadata and loudness log boxes.

I think I discovered the issue. It looks like the files I was editing were marked as "Read Only"... which is odd, because I was able to actually edit them and they did eventually save.