Does the windows event log show any entry during these crash periods?
@Hans: I have checked the windows event log, but there seems to be very normal.
Here is more details about the server. See the remarkable CPU peak in the attached image.
Dell PowerEdge R710 (CPU=Intel Xeon 2.26 GHz, RAM=8GB) OS=Windows Server 2008 64bit
java version "1.6.0_23"
Java(TM) SE Runtime Environment (build 1.6.0_23-b05)
Java HotSpot(TM) 64-Bit Server VM (build 19.0-b09, mixed mode)
Maybe the file m2ee_log.txt, also in the Log folder) shows some information?
Did you run the last Mendix Service Console, version 1.0.6.2? You can see the version number in the titlebar of the Console.