In my opinion you need to get rid of the MCP in favor of an MP20 running 4.53c. The MCP is a dog.

Save the MCP database and then you can do copy/pastes manually over to the installed MP20 for most of the data.

If you can't do that then take the MCP back to 4.30. That is the last version that seemed to run trouble free on an MCP. Data will need to be entered manually.

When upgrading the MCP if you went from a software ver pre-V4.30 and did not go to 4.30 before continuing forward that is your problem.