Microsoft OLE DB Provider for SQL Server error ''80004005'' on Load Balancing

I have posted this also in one forum. Somebody might have idea here.

We have four Windows 2003 advance servers with SP 3 configured on NLB.
Each of them has one NIC.
Recently we started to get frequent time-out error messages from web applications on those servers when they try to establish the connection with the SQL 2005. If you run web pages application to connect to sql server 10 times, 9 times you will get good connection results and 1 time you will get time-out.

Microsoft OLE DB Provider for SQL Server error '80004005'
Timeout expired
/common/mypage.asp, line 20

Connection to sql server is established with the connection string. Any idea how to solve this problem? Is there a connectionproblem? from NLB to Web to SQL?

We have tried doing some suggestions (e.g. LMHOST, IP, domain account for WEb to SQL connection, the Query Wait in SQL advance property.), but seems this timeout expired still exist

Thanks in advance...

We thought it was only in IIS and Firewall pooling connections. There were open connection threads on IIS, where in fact the firewall already disconnect it. When a new request from IIS is set, sometimes it uses the aged out connections. This was one of the cause. What we did is modify the timeout connection from firewall 1 minute more than the IIS timeout expiration. Though we still encounter timeout expired once in a while. Any idea?

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Another thing that might help to analyze this issue:

I tried to check the Profiler for the timeout expiration. On the Profiler, SQL grants login (AuditLogin) but kicked it out right away (AuditLogut) for that specific timeout connection. No duration cost.

sql