[Solved] Weird sudden mono output.

Here's one for you nuts and bolts guys. It's most probably my stupidity, but I suddenly have mono output from an old project. What happened is this. I opened an old project from 2007 and was in the process of slowly rebuilding it with my current slate of plugins (I'm currently using X3) and I was in the process of deleting plugins that are missing. I forget which plugin it was, but the second I deleted it from the master bus, everything went mono. I double checked, and the output on the Master is set to stereo, the tracks are set to stereo and yet it's all coming out mono. If a solo a track and pan it, it will pan but it's not in stereo, same with the master bus. I checked my output meters from my quad capture interface and I'm getting 2 channels of.....mono. What magical switch do I have to hit to get my stereo back? I started a new project and inserted Kontakt 5 and loaded Abbey Road drums and they're now coming out mono by default now too....Thanks for your help. It's always something.....lol...
 
Found the same issue in another thread. Turned out it was just a matter of deleting plugins and closing and reopening the project a few times. Sure would like to know what exactly happened though....

That was my guess too. I deleted everything, still mono. Closed and reopened the project several times and it finally healed itself. The mystery of bits and bytes.....