Q: My mbp will not go past the white screen.

Downloading Mackeeper was a mistake.  I hope that you have your data backed up.  If so I would reinstall your OS and start fresh.

Mackeeper is essentially a fraudulent piece of garbage ware.  For more details on this search this forum.

Ciao.

I assume you mean Snow Leopard (To install Lion on a MBP, Snow Leopard is required, not Leopard.)  You can In stall Snow Leopard and I would suggest you down load Lion again, install it and then transfer you data backups.

There probably is an easier and quicker way but right now can't think of any (I don't use Lion).  Perhaps some one will read this and give a more efficient method.  I'll look around and see if I can find some thing.

Ciao.

See if you can Boot to Recovery with Command 'R'.  If you can, then erase disk and install Lion.  this could save you time.  Read this:

Ciao.

Here is the Apple support info:

http://support.apple.com/kb/HT4718

Ciao

Here is information on Snow Leopard.  If this fails to correct the situation, then I am suspecting the problem may be with the HHD.  An appointment at the Apple store Genius bar should be the next step.

http://support.apple.com/kb/HT3910

Ciao.