Exploit/MMS.A is a corrupted MMS message that causes a buffer overflow in Windows Mobile devices that use versions of Arcsoft MMS composer predating August 2006. The exploit code is device specific, so that if the exploit is not crafted for the particular device type that receives the corrupted MMS file, the only result is a crash of MMS reader application. Thus this exploit is low risk.
Allow F-Secure Anti-Virus to disinfect the relevant files.
For more general information on disinfection, please see Removal Instructions.