Well that doesn't matter as my comment was directly to yours.
ctfmon can be both a valid program, in XP, or malware. Check the files Properties to see where it is located and if it has a proper Digital Signature. Also check the Timestamp and Details both in Properties; i.e. on each computer to see if they make sense.
ctfmon files have been known to become corrupt which could be created your problem.
You were talking about the detection being on ctfmon.exe and it never was on that file. not the scan type or if a custom scan undertaken.
Reread the topic the OP makes that point detection on one not on the other, so a deal of reading between the lines is required to make the assumption.
However, I wasn't bothered about why it wasn't detected on the one system, only why there was a detection on the other and that was because it was a custom scan with a memory scan also selected as shown in the image posted by the OP in Reply #4.
