Only an observation..
IF you still have the trial version of SUPERAntiSpyware Pro and MSE installed......
If you go to the MSE Community Forum and ask if the two conflict, you will receive a resounding YES! You will also find the same written within "Microsoft Security Essentials - Installation Checklist and Frequently Asked Questions ".
However, if you go to the SUPERAntiSpyware forum, many say the two co-exist without a problem.
Again "if" SAS is installed and running in real-time, have you tried disabling it to see if it makes a difference?