Problem with Alter Table

Hi, Has anyone encountered a problem with Alter Table, ie trying to drop columns from a table. I had a table of about 150000 records (each record having a text in a blobspace), and when I tried to drop a column (just an integer field) from the table using dbaccess, I had a "Invalid message from sqlexec" message, and refuses to drop the column. Then, when I did a unload of the entire table, I found that I was short of 50,000 records....thank goodness I had backups. A quick check using dbaccess confirmed the 'lost??' of 50000 records. Anyone has any ideas why this occured, and is it ever safe to use the alter table command? Rgds.