MRU's are "most recent(ly) used" items/apps.
Have a look if this helps , this is for an infection that causes popups , but is invisible in an
hjt log:
Please download AproposFix.exe -
http://swandog46.geekstogo.com/aproposfix.exe
Then boot in Safe Mode, double-click aproposfix.exe and unzip it to the desktop.
Open the aproposfix folder on your desktop and run RunThis.bat. Follow the prompts.
When the tool is finished, please reboot back into normal mode.
Post the entire contents of the log.txt file in the aproposfix folder.