Error in commane line, what does this mean?

Hello,
evryime i start up my laptop (os: windows xp), on the desktop the prompt message comes up that says ' error in the command line'. can you tell me what this means?
Also, my windows appearance automatically changed to windows classic style and will not change to windows xp style, like it was before. as a matter of fact, the windows classic style is the only option there. how can i change this?

thanx in advance!!!!!!!!