Microsoft Security Essentials - Is It Really Scanning To Your Sheduled Settings?

I am concerned that Microsoft Security Essentials [MSE] is not performing as it should, because it doesn't appear to be activating and running a scan as scheduled under Settings.

If I open MSE and choose to click on the Scan Now button to carry out a Manual Scan on demand, then three events are clearly visible in 'real time' -
There is activity on the progress bar of the window that opens, and files being scanned are clearly seen. The MSE Icon in the Notification Tray shows rotational movement indicating that a scan is in progress. and, At the end, a summarised report window opens. Example here -

this shows how many items were scanned, and reports on the 'threats' status.

I have tried to verify my claim above, by carrying out a number of 'tests', primarily to try and determine if User scheduled scan settings, are actually initiating the automatic update and scan by MSE.

The scheduled 'test' scan times have come and gone, without any visual evidence to show that MSE has automatically activated and conducted the scan, as set by User settings. None of the following show any evidence of a scan either starting, being 'in progress', or ever being carried out;

The MSE Icon does not activate. There is no post-scan report [as shown above from the manual scan]. and, A check of Windows Update, shows that no further Updated Definitions for MSE, have been added to Update History. I am beginning to suspect that because I use Firefox as my default browser, somehow this may disable or immobilise the automatic scheduled scan function of MSE. I also wonder how many other Users are experiencing the same difficulties.