getting an error on MC server please help :(

[Freddie589]

hey guys,

whenever i start up my minecraft server using MCsharp this message just repeats itself in the CMD window:

could not load file or assembly system.core version=3.5.0.0, culture=netural,publickeytoken=b77a5c561934e089, or one of its dependencies the system could not find the file specified

i am also unable to see anybody elses blocks in the server and they cant see mine.

how do i fix this?

thanks,
freddie589