I wouldn't worry about the desktop.ini files - you can always view them and see what they contain. In almost all cases they are harmless and can be kept or deleted, as you prefer.
The about:blank issue, though, may indicate that you have a browser hijacker present. This may be connected with the 5 files that McAfee has detected and quarantined, I can't say.
If you have a Potentially Unwanted Program on your system McAfee may choose to ignore it, but a program like AdwCleaner or Malwarebytes will flag it if it's there. If you run those two you'll have an extra level of confidence. Of course there are sets of cleanup programs that will scour your machine from memory to disk and back again, but those two are good enough to cope with 95% of relatively minor infections.