This virus is probably written by the same author as the PSQR variant of the Jerusalem virus, as it checks if that virus is present, when it is run. This virus will overwrite the last 32 bytes of any file it infects, possibly destroying the victim. Prudents activates on May 1st - May 4th of any year, interfering with disk writes.
Allow F-Secure Anti-Virus to disinfect the relevant files.
For more general information on disinfection, please see Removal Instructions.