Partition Problem

I have 160G harddrive and two partitions. System partition has 13G and i tired extending it to 20G but for some reason I cant. When i used it to extend the regular partition it worked but when i tried to extend the system partition( Win XP Media OS) it didnt work. I also used norton magic partition but it still dindt work. I complete all the necesary steps and asks me for restart. WHen i restart it shows that dos is running and trying to convert but when windows run it didnt have any effect.The hard drive was installed by Sony; COuld be somehow encripted or locked? ANy ideas why? Or maybe I have to do something else?
Thanks

 

Take a look at this thread if you haven't already.

Booting from the rescue cd to perform these actions sometimes works better than beginning the process in Windows and then it having to reboot to finish.