My computer lags but stops when i hit it....is it a mule?

hi all,

i have an issue with my computer, is that maybe once or twice a day, it gives me a lag spurt of 0.5 seconds for every 1-2 seconds.....before, i used to turn off everything in the task manager, plus turn off most services from services.msc and still the problem would not be solved....until i restarted the computer, so i was sure it was software and would need antivirus/malware..etc . . . it was only recently that i realized that hitting the laptop at the bottom on the right and left side where the touchpad is, stopped this lag!!!
what could it be, if its hardware, how come it goes way after a restart (not always), and if its software, why would hitting it make it go away.

ps. what hardware could be loose to cause this?? i'm not a professional but i've been using computers for over 18 years now, ive never experienced anything like this before

Note: this computer has the HP 3D DriveGuard which helps it take hits....could this have anything to do with it??

thanks again in advance

i have a HP Compaq 8510w
intel core (TM) 2 duo
T9300 @ 2.5 ghz
772mhz, 3.00 gb ram (4 actually installed but i guess XP limitations)
running windows xp professional version 2002 SP2

 

thanks for the reply, i actually ran all the diagnostics in the seatools (for seagate hdd) and everything checked out perfectly. any other suggestions. (i'm tot
ally with you on the idea that anything loose would cause the BSOD or it wouldn't allow the computer to run at all) . . . weird issue

 

hmmm, so it IS possible something is loose?? interesting, guess ill be opening it up to check on that cuz it doesnt seem right banging it like that other option of reflowing sounds great, ive had it for over 3.5 years now, so it cud be an issue.....too bad hair dryers wont work thanks guys !! this is very helpful