ERROR 2318 INSTALLING UPDATES

Hi All,

I currently have SW 2010 SP 4.0.  I tried to open a part file today that I had been working on the day before and this message appears:

Invalid class found in file

The file closes and Im not able to do anything with it.

So right now im trying to install the latest update, SP 5.1 and now im getting this error:

Error 2318.File does not exist: C:\Config.Msi\PT52C.tmp

Has anyone experienced this before or know what I can do to fix it?

Thanks!

SolidworksAdministration