Skulls is a malicious SIS file that will replace the system applications with non-functional versions, so that all but the phone functionality will be disabled.

The Skulls SIS file is named "Extended theme.SIS", it claims to be theme manager for Nokia 7610 smart phone, written by "Tee-222".

If Skulls is installed it will cause all application icons to be replaced with picture of skull and cross bones, and the icons don't refer to the actual applications any more so none of the Phone System applications will be able to start.

A screenshot of how your 7610 will looks like if you got the trojan

This basically means that if Skulls is installed only the calling from the phone and answering calls works. All functions which need some system application, such as SMS and MMS messaging, web browsing and camera no longer function.

If you have installed Skulls, the most important thing is not to reboot the phone and follow the disinfection instruction here

http://www.f-secure.com/v-descs/skulls.shtml via www.engadget.com