Updation of table exception

Hi,
We have developed the TCPIP Server - Client communication application using .net 1.1 which will spam a maximu of 10 threads at a time.
Each thread will access the Table in a SqlServer 2005 Express Edition.
But my problem here is the updation of table fails due to some exception.All the exceptions a record at a time difference of around 1 to 5 seconds
I Suspect that the problem will be more than one thread is accessing the table for updation process.
I like to know how the sqlserver works if above type of situation arises.
Thanks
Ranjith

Can you post the exact error message seen in SQL server logs in this case ?
Please read on locking mechanism in SQL server in following link to get better understanding on this
http://www.sql-server-performance.com/articles/per/advanced_sql_locking_p1.aspx
http://www.informit.com/articles/article.aspx?p=26949&seqNum=3
Regards
Sat

Hi All,
Thanks for your response.
Actually before updating the table we are executing a select query.
For this we have created an index.Because of that the issue is solved.
Still we are mojitoring the system and looking for the exact error once we got it i will post the same.
Thanks
Ranjith

Hi All,
Thanks for your response.
Actually before updating the table we are executing a select query.
For this we have created an index.Because of that the issue is solved.
Still we are monitoring the system and looking for the exact error once we got it i will post the same.
As you said the error we got only at the time the connections are high.
and i don't think hard ware could be the problem,because the system is having a very high config and with latest service packs.
Thanks
Ranjith