From your response, your hard disk did likely go to sleep after a set period of time (you said you changed the settings afterwards) and that may have ended up causing a corruption in your case database. Completely starting a new case may yield the results you are looking for, but it is possible that your Autopsy installation (and user settings, preference, etc) may also have been corrupted with disk access being halted due to the original settings, which according to your statement, have been changed, but it is possible that the corruption issue is already present and nothing short of a completely clean re-installation will fix it.
Again, its hard to say for certain, but based off a quick search for a couple other results of what you are seeing, it looks Autopsy data corruption, due to the original settings of your disks going to sleep after a period of time, is most likely the cause. (A search for “http://localhost:23232/solr” on Google will yield plenty of similar results, but I only listed two below)
https://sourceforge.net/p/sleuthkit/mailman/message/35509888/