It's been quite a while now, but there were a number of cases of oddball issues with Microsoft Security Essentials conflicting with MBAM Pro's real time protection and subsequently, a few suspected cases of conflicts with Defender on Windows 8/10 and MBAM. The logical reason for not having multiple real time protection programs running is that each will require access to the item being monitored before it will be allowed to freely proceed. Depending on how the protection demands access, this can cause a deadlock, however momentary, while one waits for its turn to peek at the footprint of the file/code that is coming into memory of writing to disk. Performance may be impacted, and in some cases, a failure due to a timeout parameter being exceeded. On a more powerful machine, performance may not be noticeably impacted and if the protection programs are well written, there should not be any instability, but the risk is still there. I have personally not experienced issues running MBAM Pro and Defender together in my testing.
-steve
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stephen boots Microsoft MVP 2004 - 2020
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