if your still scanning with MBAM and it's not moving, open task manager and end task....
I did forget your computer is XP
https://www.eset.com/us/home/online-scanner/
the above link is the same scanner but with a different approach
Operating systems: Microsoft Windows 10/8.1/8/7/Vista/XP/2003/2000/NT (32/64-bit)
Internet browsers: Firefox, Opera, Chrome, Edge and Internet Explorer 6 or later
try this one and use the same method to disable your system security to allow it to run.
If, this wont work either
free KasperskySecurity Scan
https://usa.kaspersky.com/free-virus-scan