origininal error message after running exec [sp_ShowContigAll] 0,1,95 was
"Msg 2588, Sev 16, State 3, Line 1 : Cannot find partition number 1 for index ID 19, object ID 803586001. [SQLSTATE 42000]"
I ran dbcc checkdb and check alloc and both returned no errors, the db is perfectly normal. But I also found my own answer too.
Some other admin had started "Database Engine Tuning Advisor" and the process died unexpectedly and all the Hypothetical Indexes and Statistics
were not cleared. The index pointed in the error message is one of those, so I cleared all of those with this script and reindexed the db with no problem. I hope it helps some others.
select 'drop index ' + b.name + '.' + a.name
from sys.indexes a, sys.all_objects b
where a.object_id = b.object_id and is_hypothetical = 1