why does my Dell mini netbook shut itself down and have immense problems starting up every time i close it?

There may be a virus, i think you may have to do a system restore, my advice is to get it to start up once, then back up all your information, to CDs or flash drives. Then do a system restore. It can be found by going to Start-All Programs-Accesssories-System Tools-System Restore, that only if the recovery is pre installed, if yours came with a recovery disk (separate CD) and using that. If it will not turn to your start screen, then when it turns on keep pressing F8, and it will bring you to a screen with options, pick the one that describes your problem best and click it.

Hope i helped!