Pocket PC Fujitsu-Siemens LOOX 720 is heating up to much!!

i have my LOOX 720 for 2 weeks.it is Second-Hand and after playing with it i realised that the back of the PDA is to warm..
Then i pulled out the battery,that was 2 warm from my experience!
then i've done a simple test:
with the battery out of the LOOX ,i managed to make it work only with the AC power plug..after 5 min of playing Spiderman.avi(400x340 Pix) with TCPMP
with full backlight ..the device was warming up like
then..after cooling down ,waited about 30 min ...i played some mp3's with TCPMP with screen of.. and the device was warming up..but that much!!

btw..my battery last at maximum 1:20 hours fully charged wathcing spiderman.avi with light at minimum and the Procesor Mode to Auto!

another day i tried to play Worms..that was fine..working good..ti'll batt dropped..to 10%..and i went for the AC plug to contiunue my game...
after 1 min..i get a WARNING from Win that tells me my batt charging function will go off..beacause of the High Temperature!

pls ..is there something i can do?!