Also, there is a utility that was posted in another thread (can't find it for you 🙁 ) but it can analyze the reason why it did a memory dump.
It creates a file in the windows directory, do a search on your comptuer for *.dmp it'll be close to the size of your physical RAM, 256 MB, if you choose not to do any thing with it delete it, it takes up space on your HDD.