Hi, I'm new to Solidworks and recently I was having what is apparently a common issue installing the program. I was unable to click the next button on the installation manager. After going through many, many, many, tutorials online I was still having no luck. I found a comment on a random website unrelated to solidworks from an individual who stated they found Mcafee anti-virus caused their problem with being unable to install certain programs. I had uninstalled mcafee 6 months ago so I blew this off at first until I later stumbled across the information that using the windows uninstall for mcafee is simply not enough. There is an uninstall program from mcafee, which I found online, ran the program and to my delight the installation manager worked as designed. So:

If you have Mcafee and you are getting the "unable to click next issue", it may be that you need to completely uninstall mcafee. First through windows, then through the mcafee uninstall tool.

I hope this helps. Thanks.