Why is it taking 6 hours to render a 23 minutes audio file with a png for mp4 ? H264 format.

Ok... just last week it was working fine, and I don't know what is different this week, but it is taking way too long.

Here is what I have:

1 wav  file 23 mins :30 sec   long

1 pgn picture spread for the 23 mins video

1 mp3 file background music spread for 23 mins

 Sequence setting at 1280x 720 pixel size

When I send it to media encoder I have:

format: H264

Preset: Match Source - adaptive High Birate

Ouput file:   the place where I want it.

Then I hit the the green arrow to start.... and I have 6 hours to encode 20 mins?  

^^^^  Why is this happening and how can I fix it to encode faster as it was? 

BTW...  I recently updated premier pro, and my media encoder is up to date as well.