I can assure you I am a real person; a little beat up at the end of tax season, but still here. :]
There's some type of system matching problem at the IRS that keeps popping randomly with respect to e-file attempts getting rejected for no apparent reason.
Currently, there's no solution, and it's not likely to be corrected any time soon as to date I am not aware of any resolution of what is causing the problem.
In order to avoid wasting a lot of time, with no guarantee of success, the recommendation is to simplify file a paper return and avoid the problem all together.
It is highly unlikely that anything will be resolved by midnight tomorrow, so the only other alternative is to file for an automatic extension and pay any balance due using one of several alternatives, including simply sending along a check, with either a payment voucher or the actual paper extension, just like the "old days".
All I can say is that you are not alone as there are many, many taxpayers having the exact same problem.
Please remember to rate my response as that is the only way I will receive credit from the site for assisting you today.
Thanks very much,