Sorry for resurrecting a dead topic but we, iolo technologies and creators of System Mechanic, wanted to provide some insight for you and any future users who stumble upon this thread.
We'd like to let you know that the MFC45 file is not corrupt or harmful in anyway. How do we know? We created it!
The file itself was created as a way to provide security for our users and their product licenses as a result of the rising cracks and hacks for System Mechanic.
We are aware that this file has sometimes been mistakenly detected by certain antivirus programs and we've addressed this issue in the latest update this week.
Lastly, we are also working on a solution that does not require this file. We plan to have this fix addressed in a future product update. We hope this information helps, thank you!