Why am I getting error messages when trying to search for cases in CiviCase?
I began to examine the case types more closely. Some had matching Name and Title, others did not. Previously, you could change titles but not the Name as they were created in the program files and had to remain as they were.

In any case, next to the Name display there is a lock. I unlocked the lock and then saved. After doing this for each case type, everything began to work fine again. 
I do not know why this worked nor if it will be permanent but for now, the program works fine.
(btw, I had upgraded to Civicrm 4.7.4 before doing this, but the upgrade did not solve the problems at all)