In a workbook two of my spreadsheets will not load past row 56

In a workbook two of my spreadsheets will not load past row 56

I am getting an error saying that the server has encountered a problem.
It later says that there is a failure in collaberation mode

This is happenning on two spreadsheets in a workbook of 6 spreadsheets 4 of them work OK so I suspect it is a problem with the spreadsheet raather than the server?

Help!