This is a complicated stealth virus, which infects files when they are accessed. Occasionally the virus displays this message:
ALPHA STRIKE Advanced Tactical Viral Implant by NEUROBASHER'93 / Germany
See: Tremor, Nightfall, Neuroquila.
Allow F-Secure Anti-Virus to disinfect the relevant files.
For more general information on disinfection, please see Removal Instructions.