I am running SQL Server Express on a Windows XP Embedded box. It runs for a day or two, doing some transactional processing for a POS type system, and with another system pulling data out to an OLAP DB for processing. After a while, I see in the event viewer the sequence SQL Server puts out when it restarts, copy rights, command line parameters, and so on. It seems like that coincides with our OLAP process crashing. I then see that when it restarts our transaction DB, it does a recovery, pulling in 10K or so in transactions that need to be rolled forward. Does this mean SQL has crashed? I don't really see much to indicate what happened.
I noticed I have my memory limit set to 1MB per query and 2TB for the server. These are the defaults. I only have one GB in the box. We have seen SQL crash a whole box by just using all the system memory. In this case though the whole box is up when we get to it.