n93 not enough memory close some programs

i have a 2gb memory card. ive updated my n93 to latest firmware. i have put several programs on my phone and saved them all under the minisd not the phone and ive used up about 40% of the minisd card. if i go to tools then file manager and look up free space on my n93 it says 46 mb free 4mb in use. if i hold down the blue button on the n93 that opens up what programs u have open it says nothing other then standby. so my question is, how come when i try to take a picture sometimes or play a game it says not enough memory close some programs even though it shows i dont have any programs open.... are there programs open i just dont know about? is there a program that is easy to add to my phone that will tell me what programs i have running? please help me and thanks so much!