Yes, my client received a similar letter.  Working through Proseries' worksheet it appeared IRS was incorrect.  So of course and contacted IRS (no easy feat these days) and was told where to fax in my worksheet for IRS to address the "processing error".  Then we get a letter saying we should amend the return.  I'm fuming since that would mean amending it what was originally filed.  Anyway, I go back into Proseries to draft the amended return only to see the worksheet numbers changed.  Looking closely at the original worksheet calculations and the current one, the wording on line 9b, adding a comma to the instruction which now changes the value being calculated.  Thanks Proseries for making this change and not bothering to communicate with us.  An alert would have been nice, if nothing else.