"Unknown Error"

Hi,
I have a database in mssql
I connect to the DB using TADOTables
along with the normal fields I have Lookup fields as well
when I am running my application Delphi gives me many
exceptions with the string : "Unknown Error" - which by delphi help books should never appear. this error accours but the user doesnt see a thing (not normal exception)
altough the code is not in a try except block. when Im trying to debug the problem - I cannot do it it just appear on the create of the datamodule (I dont have any code written in the on create or on any table events).
I noticed that when Im taking of the lookup fields from all the tables I dont recieve the Error (not a specific field but all of them , I tried taking them off one by one - didnt help).
does someone knows what could be the problem?
did anyone ever had this bizzare error?
if you know what to do or you some suggestions please
answer me
thanks,
bagon