I have a Mac running OS X V.10.5.8, with a 2.4 GHz intel core 2 duo processor, and I have been downloading SU 8

Ok well I have been using sketchup the past few weeks with no problem. As I got a better grasp of the program I found out about plugin's and found one that I was interested in using (SoapSkinBubble Rel 1.0.13) and when I could not get that to work I tried (Curviloft 1.2d+Libfredo6-v4.7a). With both of these I put all the files in the plugin folder of SU and they did not appear in the program. I then looked under the toolbar menu, and then at the extensions to see if I needed to check them as I have read sometimes needs to be done, but they did not appear there. The strange thing is that when I went to "Get Info" for the SU app, they were listed under the "Plug-in's:" as if they were installed.
I tried uninstalling and reinstalling both SU as well as the plugins at least 4 or 5 times, along with other attempts to fix these issues to no avail. I then decided to try a different plugin (Free version of Maxwell Render) which has its own installation manager. After proceeding through the manager I opened SU to see if it worked and I continued to have the same issue, I could not find it. Shortly after that SU crashed without drawing anything. When I went to open it again, it crashed. I uninstalled everything, restarted my computer, and then downloaded SU again, and it continues to crash every time I open it right after choosing a template.
I have spent about 6hrs trying to figure all this out and I still literally have no idea what could be causing these issues. Considering that I am trying to model some things for my college courses final project that is due this coming Monday, I need to get this figured out. At this point I just want SU to run, even if I can not use plugins. I would like to thank the sketchUcation community for all of the information that you all have provided about SU through this website. Any help would be greatly appreciated, and thanks in advance!