at \\server 21:00 "c:\virus.bat"
here is the breakdown of the AT command.
The AT command schedules commands and programs to run on a computer at a specified time and date. The Schedule service must be running to use the AT command. AT [\\computername] [ [id] [/DELETE] | /DELETE [/YES]] AT [\\computername] time [/INTERACTIVE] [ /EVERY:date[,...] | /NEXT:date[,...]] "command" \\computername Specifies a remote computer. Commands are scheduled on the local computer if this parameter is omitted. id Is an identification number assigned to a scheduled command. /delete Cancels a scheduled command. If id is omitted, all the scheduled commands on the computer are canceled. /yes Used with cancel all jobs command when no further confirmation is desired. time Specifies the time when command is to run. /interactive Allows the job to interact with the desktop of the user who is logged on at the time the job runs. /every:date[,...] Runs the command on each specified day(s) of the week or month. If date is omitted, the current day of the month is assumed. /next:date[,...] Runs the specified command on the next occurrence of the day (for example, next Thursday). If date is omitted, the current day of the month is assumed. "command" Is the Windows NT command, or batch program to be run.