I'm currently suffering from the same issue. All the performance tuning in the world is still leading to this error message:-

'The instance of the SQL Server Database Engine cannot obtain a LOCK resource at this time. Rerun your statement when there are fewer active users. Ask the database administrator to check the lock and memory configuration for this instance, or to check for long-running transactions'

This has only recently started to affect all the databases' on two differnt SQL instances which suggest it isn't a configuration but maybe a hardware issue. Using both profiler and DMV's I can't find any actual locks???!!:crazy:

If anyone has experienced this please help??!