>How can I avoid this message when I try to increase a char field from 60 to 80?
>
>

>'MyTableName' table
>- Unable to modify table.  
>Timeout expired.  The timeout period elapsed prior to completion of the operation or the server is not responding.
>

There is a setting in SQL Server 2005 Management Studio that may effect this:

Tools - Options - Designers - Table and Database Designers - Override connection string time-out value for table designer updates:

I had this same problems changing some column definitions in a large table, and needed to increase that value to 30.