My fiancee has an 04 Civic EX.
She told me that today when she got in it, the gas gauge and speedometer did not work. I told her to stop driving, pull over, shut the car off and start it again...and it worked, but she had been driving all during the day...starting and restarting and it never worked until that one time. This is the second time this has happened in the last year or so.

That's all the details she gave me...I will ask her later/if it happens again about what is and is not working.

Any suggestions now would be greatly appreciated!
Thanks!

 

My guess is a faulty gauge assembly. Run a self diagnosis:

 

use the self diagnosis system. It will find out the error.