Windows Mobile phone owners may want to check out their calling history to make sure there are no unknown international phone numbers being called – that's because there is a virus/trojan going around that is causing all of this to happen. From the looks of it, the culprit looks to be a game called “3D Anti-Terrorist” which loads a trojan onto the handset and is time triggered monthly to spontaneously dial certain international numbers. You'll also probably be getting a nice surprise waiting in you monthly bill as well – so it looks like you'll have to make some phone calls to persuade them to help you out. In trying to correct the problems being caused by this, there are some options being offered by the team over at XDA Developers
that requires you to delete some files, but performing a hard reset would likely be the best solution.