I've seen the same problem described better on another site. Same conditions... A clean Yosemite OS. And a new download of Sketchup. It's not "Finder" that's crashing. It's the "in program " access to the file system. So in Layout, it won't create the window that accesses the file list more than once. In sketchup, it won't create the window that accesses a texture list or when you want to add a local component library... It won't create the window that accesses the file system to locate the reference file more than once.
I've rolled back to Maverics until this is solved. I wonder... Just prior to wiping the computer there was a OS Yosemite update. It included a security update and it might be what slowed the startup on my Mac. On reinstalling Sketchup on Mac , there's always that caution that you're opening a program that is downloaded from the internet. What if it's the OS interfering with the program accessing the file system because it's not recognizing the app author?

I have the problem that I can't get SketchUp to open a "finder" style window on Yosemite. Sketchup 2015. Completely wiped the computer a week ago and did a clean install of Yosemite because the 2011 Macbook Pro was taking 5 minutes to boot up. Now SketchUp won't open a window to find textures, files to open, components to add to library... nothing without shutting down the program each time, and then I can only get ONE instance of a "finder" window to open before it hangs again. This didn't happen prior to the clean install, so I don't know if it was a function of the previous OS (Maverics, Lion, etc) being on the hard drive, or previous versions of SketchUp being there. It also crashed with every attempt at using a font outside of Arial for an extruded font today. I can't add textures, or open texture libraries. I can't add components from a library or open other libraries without quitting SketchUp and restarting each time. I've got the same issue with Layout. Can't insert a file because it won't open a "finder" window to locate it without closing the program and re-starting it. MADNESS!!!!

Something I just noticed... sometimes.... the toggles look like the scale tools in Sketchup... like there's three across... THAT's when it crashes. If I click away, and try the tool again...sometimes... the toggles remain singular, and then (as in the last two tries) it works. If the toggles are oversize and all black... it's like the tool launched incorrectly, and the crash happens. If this is how I have to work... then so be it. Got to get these drawings out tomorrow.

Still trying and still frustrated in geting fredoscale to work. All files are updated. Computer re-started from a cold shut down. Only other plugin is mirror. All I really need is the fredo toolset. Mirror works. I had some idea that it was the z axis that had problems, but no. Sketchup closes with any movement or attempted movement of the toggle. Every file in the plugins folder is read and write.

What would be the correct way to remove everything and re-download and re-install? Can I just delete them from the directory? I'm not sure which files are which now that it's been extracted to the plugins folder.

Yikes.

I checked the read and write settings, and changed "everyone" to r&w just in case it didn't see me as admin. first two tries, it worked. Then crashed the next 6 times. Went to the sketch up root folder above plugins... Made sure it and all it's contents are r&w... Rebooted sketch up... And crash. It allows me to select the tool, position the grid, and the as soon as I select the toggle on that axis... Sketchup closes. Same as always... But for two brief seconds I was smiling...

I'll try a complete system reboot and check to make sure it's still all r&w... But any other suggestions?

ShetchUp crashes. Shuts down. Closes. Work reverts to last saved version on reopening SketchUp. I've learned to save before trying to use the tool so I don't have to go dig out the autosave file.
Fredo Scale and all the Fredo Tools were downloaded exactly as detailed in the user download and installed and working perfectly before I upgraded the OS from 10.7 to 10.8, so I can only assume its the upgrade.
I'm going to try a reinstall later today, but wondered if anyone else was having this problem after upgrading. If not, I may have another issue going on...OR the tools need tweaking in order to work with 10.8. I'd just like to have an idea which it is before I go messing around with files that used to work... And waste more time.
I tried updating LibFredo6 to v4.6c, and that did nothing. (previous to the upgrade I had 4.6a working). Purging the outdated files in the folder via the upgrade screen didn't help either. Kind of frustrated because I've come to rely on the ability to correct sizing on my construction drawings with the ability to choose where the stretch or shrink should occur.

Issue with it crashing SketchUp Pro 8. Now running OS 10.8.1. Crashes on even the simple things. Can it be fixed? Is it the OS? I'm only trying to use Fredo Scale.