Sql-server – SQL Server 2005 SP3 version 9.00.4035.00 vs 9.00.4053.00

LSASS is the Local Security Authority process. LSASS does any work only as a result of security related activity occurring on other processes. A high amount of lsass.exe activity would indicate perhaps a high number of authentication (Kerberos, NTLM) events occurring.

Forget about Task Monitor or Process Monitor. Fire up Perfmon and look at the performance counters if you want to troubleshoot a problem. Get all counters/all instances for the Process category to identify which process consumes CPU/Memory/IO. I would be quite surprised to hear that lsass is truly a performance bottleneck.

I'd recommend you follow the Waits and Queues troubleshooting methodology to understand why you experience problems at peak hours. It's a proven methodology with an stellar track record on identifying problem root cause.

Sounds like you were on the correct path. Errors like this are caused be previous pieces of software being installed that what you are now install conflict with.

In this case SQL Server 2005. I would ensure you have no other versions, if you have say MS Visual Studio and did the default install this install a version of SQL Server. So you might need to go into that in the Add/Remove software wizard.

If you have indeeded uninstalled all aspects of it you might have a broken install somewhere. You would have use to use the MSI uninstall wizard however this has been depricated for MS FixIt:

http://download.microsoft.com/download/D/7/E/D7E37511-A7CA-4C8B-B61B-1C90895D9823/FixitCenter_Run.exe

Hopefully this will find your problem and you can then install SQL Server or just the Client tools. This is the command line options for doing so and has saved me tons of time, replace the version number for yours I think this will works for both 2005 and 2008

start /wait "SQLTools2008" setup.exe /Q /ACTION=install /IACCEPTSQLSERVERLICENSETERMS /FEATURES=ADV_SSMS