Keeps checking for wifi!

S3 i9300 The One Plan on 3

When using the personal hotspot, I keep getting a pop up that tells me that switching to wifi will disable the personal hotspot - it gives options, OK or Cancel. It doesn't seem to cause a problem, but is irritating.

The pop up suggests that something in the phone is repeatedly checking for wifi, and trying to turn it on, which must be using battery.

It doesn't happen when I'm not using personal hotspot, and wifi is disabled, so it seems to be active only when personal hotspot is active.

It could be an app, or it could be something built in?

Very strange! Any ideas welcomed.

Many Thanks

Richard