Excel keeps changing to Manual Calculation

[zookeepertx]

Hi guys,

Here's a weird thing: Yesterday, sometime between about 3:00-4:00, apparently my Excel changed itself from Auto Calculation to Manual. I didn't do anything that should have made anything change and had been using the spreadsheet I was working in several times through the day with no problem.
This morning, I changed it back to Auto Calculation and things were fine for a while, but then, maybe 15 minutes ago, it changed back to Manual Calculation, all by itself!

Anybody have any idea what might be going on? (Besides the idea of gremlins in the works, LOL!)

Aside from that, when it DOES calculate, it's not giving me the expected answers!

Thanks

Jenny