SW 2017 SP3 not installing.

I'm having an issue with Solidworks 2017 SP3 update (updating from 2017 SP2) as it stops installing during the system check. I dont get an error, it just stops at the 'Detecting client installations' bit & doesnt continue.

I've connected by VAR but they dont know why its doing this & just washed their hands of it. Can anyone here help?

Thanks.

SolidworksGeneral