Only in the latest version of the home software can some detections be trusted. Try opening SecurityCenter, Navigation, scroll down to Quarantined and Trusted Items and find it in Quarantine and see if that option is there.
Unfortunately there is no other way than white-listing the file that is being falsely detected by McAfee. Please follow instructions in above reply so as to white-list the said dll file. Please post back the version details of McAfee to see if we can exclude the file from Real Time Scanning provided yours being the Latest Security Suite. To check Version Open GUI > Click on About link at the bottom right. Paste here the version information for proceeding further.
If it were me I would upload the file to VirusTotal and see if it's just McAfee detecting a problem.
Pure coincidence perhaps but this is the second post about a Steam download being quarantined by McAfee. Not Supreme Commander by any chance?