manually update a table

i have 2 tables in an sql db. table1 has 2400 records and table2 has 1400 records. if i open the table and select all rows in table2 and try to manually edit the contents of a field i receive the following error:

communication link failure.

if i open the table and select top 1000 i can manually edit any value with out any problem.

if i open table1 and select all the rows i can edit any value i want with out any issues.

can it be that the size of the table prevents me from editing when i select all the rows?

extra info:
table1 has more records and more fields but the fields in table2 are larger (navchar 50 compared to navchar20)

Thank You,
ThomasDo you have a primary or unique key on your tables?|||Try to use the OLE DB provider for SQL Server instead an ODBC driver, and see whether you problem persists.|||Are you doing this in EM? If so, it is highly reccomended you do not edit data this way as it creates a big overhead with locks. Writing appropriate update statements would be better. (again, if you are doing it from EM)

HTH