system restore

[Charlie]

The only possible date for my system restore is today,
August 7th. I try to go back in months to either June or
July, but it will not allow me to do so. I am trying to do
this becuase an error message comes up every time I start
up saying some file could not be loaded, but that is
because it is not even on my computer. The startup is also
very slow, so if there is anything I can do to speed it up
and correct things, please help.

Charlie