The default Dell install I've found in every Dell I've used and owned is usually flakey as hell and definitely not pristine. They've added their own junk and usually put a whole bunch of other stuff in for other models in the same series.

One of the first things I usually do is just to wipe it and start over from scratch using a retail Windows disc and then download the necessary drivers and bits from the Dell support site. Don't go for the generic drivers from Microsoft or the manufacturer as sometimes you need the customised Dell variant. An example would be my laptop, if you download the generic sound drivers then the volume control don't work properly.