Something has happened with the indexes in your WinMORE. You need to re-build your indexes. If you have a network version of WinMORE, make sure everyone is logged out except you.
In WinMORE, click set-up and click Re-build Associate-TAX ID Index.
Close down WinMORE.
Once you re-open WinMORE it should work fine.
Please let us know if it does not.