Further update to the previous tests
I now rescanned the same file using a trial version of MP3Test.
This is interesting becuase MP3Test agrees with MP3Utility on the number of mpeg frames in the test subject mp3
MP3Test also agrees with MP3Checker that there is error, but where as MP3Checker reported Invalid frames 5% error, MP3Test only reported 0.04% error.
These are the error check reports by all three programs:
MP3 Checker: 19138 frames verified. Invalid frames 5%  Repeated frames 14% 
MP3Utility: No errors found. 19238 frames processed (0 padded, 10238 unpadded), Bitrate is variable.
MP3Test: First Frame Invalid. Resync: 2172 Bytes as 0:00 (0% through). Frames:19238. Errors: 1 (0.04%)
I would conclude from these results it is likely that MP3Checker is wrongly caculating the number of frames in the test mp3 (as the other two programs agree on 19238 frames)
I would also conclude that MP3Checker is correctly reporting that there is invalid frame error(s) but only further testing will show whether or not is correct in reporting 5% error, it is unfortunate that MP3Checker does not report which frame(s) it has found to be invalid.
Also with MP3Checker I am unclear as to what the bracket number means : Invalid Frames 5%  is the 10 an error code or the number of frames believed to be invalid ? As 5% of 19238 frames is a lot more than 10 I would be inclined to believe 10 is an error code# but I can't find a description in any documentation to verify this.