Oh yeah forgot to mention about running games

Have u tried any of the latest graphic intensive games on ur pc Kristikan? Sometimes a crash can be atributed to over heating in either - the cpu, Graphics card,and sometimes memory but not often as long as ur power supply fan is working.

Its definetly worth doing wot Happydaze saiys and turn off all non essential progs, Press CTL+ALt+DEL together,a box should pop up saying windows task manager, under Applications tab end all of the programs u see.Dont end any programs under the Procees tab unless u know wot ur doing

If u click on the Performance tab it will show u cpu usage which should be very low ( mine is at 2% when not doing anything) and available memory which should also be low like Happydaze says (i have a total of 785904 and 589364 is available while i have a few things running)

Hope this helps