Microsoft today announced that the "Visual Studio 2010 SP1 Beta is incompatible with LightSwitch Beta 1."
"Last month, the Visual Studio SP1 Beta was made available. We want to inform you that if you're working with the LightSwitch Beta 1, do not install the Visual Studio SP1 Beta as these Beta releases are not compatible.
If you want to install LightSwitch Beta 1 into Visual Studio 2010 Pro or Ultimate versions please be aware that LightSwitch Beta 1 will only work with Visual Studio 2010 RTM (released version).
If you just install LightSwitch Beta 1 please do not install the SP1 Beta after that."
If you have already installed SP1 Beta then to remove it, go to your Add/Remove Programs and uninstall it there. If you are still having problems, perform a Repair on LightSwitch Beta 1 and you should be up and running again.