2010 SP3.1 install location incorrect

I've had SW2010 installed on a logical partiton (P:) away from the system files since the first install. I've subsequently performed service packs updates to 2.1 without any problems.

Today I've tried to install SP3.1 and the location at the bottom of the summary points to the old std 'C:\Program Files\Solidworks' this is not where SW is installed. Also I thought SW had another dir. path which should points to 'C:\Program Files\Solidworks Corp\Solidwoks'.

That being said there is a change option but this is greyed out, so I have no user friendly way to change the location.

Any ideas what may cause this (I am also speaking to my VAR)

Edit.

I have two 32bit machines, both display the wrong install directory. However my 64bit machine installed as expected.

SolidworksAdministration