thanks for the replay.

> Have you checked the performance monitor (Administration Tools ->
> Performance). I would be looking at read and write queues for the
> disk, as slow queries tend to be waiting for CPU time or disk access.

This was one thing I checked at first.
I monitored the read and write processes by filemon and there was no
abnormality during the problems in the ERP.
Nothing hangs or took too much time or something similar.

>
> If that does turn out OK, then is there a possibility that the queries
> are running under a WAIT transaction, and so they are waiting to see
> if the conflicting transaction commits or rolls-back before returning.

OK this sounds logical, but how can I detect these WAIT transactions?
And when this is the problem, why it is this problem?

>
> Your database stats look OK from a garbage perspective (and you would
> be seeing a maxed out CPU core if it wasn't).

The health monitor from SBS never showed something critical.

Andi