I’ve had a quick look at your model. It opens without problems in both SU 2018.1 (on Mac Mojave) and the latest SU2021, and I have no problem dragging selection rectangles.
The most likely explanation of your problem is that your graphics driver has problems, but that is unusual on a Mac. However, you have a basic Intel graphics chip, which might possibly be the source of your issues. The only way I know of to update the graphics driver is to update Mac OS X, and you have already done that, you say. (Your profile still says you are running SU 2018 and High Sierra, by the way. If you stick with 2021 and Big Sur, please update it.)
Can you downgrade the OS to the version before? Big Sur has caused some problems for SU. If not, can you check you have the latest version of SU 2021 (you probably have, if you’ve just installed it. For Mac, it’s 2021.0.392 (Check from the Sketchup menu, About Sketchup.) And the latest version of Big Sur?
If other models don’t have this problem, It might be worth your while trying to open your model, use Cmnd A to Select All, and copy that to the clipboard. Open a new file and use Edit/Paste in Place to start a new copy of the model. Save it with a new name, and see if that helps. Close the original.
For what it’s worth, there are a number of common beginner modelling errors in your model, but they shouldn’t cause a crash. They are however worth fixing before you go further.
- First, you have assigned non-default Layers (Tags in SU 2020 and 2021) to some edges and faces. Possibly you exploded a component or group to which you had assigned a non-default layer or tag. That assigns the layer to the edges and faces after they are exploded. Open for editing each group or component in the model in turn, select all inside the group, and set the tag to Untagged in Entity Info. If all the edges and faces are already assigned to Untagged, then it will show in the Tag line in Entity Info already, but if that line is blank, some have another non-default tag assigned.
Leave Layer0/Untagged as the default layer/tag (which it is, correctly, in the file you uploaded). Assign ONLY Layer0 or Untagged to raw geometry - edges and faces. That will happen by default if the little pencil icon at the right in the Tags window is on the Untagged line. (It’s a radio button on the left, in versions of SU before 2020.)
I’ve run the CheckUp 3 plugin Geometry to Layer0 plugin to do that automatically.
- When I view your model with View/Face style/Monochrome, and Roof and Walls tags turned on, I see some reversed faces.
Click on each blue/grey (reversed) face in turn (you may have to open a group for editing first) and select Reverse Faces to fix this.
- Your plan and elevation scenes are not set in Parallel Projection, top and front views, but in perspective, and not from quite the right direction.
In the Plan scene, go to the Camera menu, and select Parallel projection, then Camera/Standard views/Top (or press Cmnd+1 on Mac). Right click on the Plan scene tab, and click Update to save that change.
Similarly, in the Elevation scene, again choose Camera/Parallel projection, then Camera/Standard views/Front (shortcut Cmnd+3).
You could if you wish similarly set up a Side Elevation scene.
Use more components for separate parts of your model. Any geometry that isn’t in a component will ‘stick’ to any other geometry that you draw, even if it is on a Layer or Tag that is turned off. And geometry within one component or group will stick to all other geometry in that same component or group.
Hope the copy/paste into a new model fixes the recurring graphics problems. If not, perhaps someone else more knowledgable than I can help with the graphics chip driver problem.
Here’s my minor update to your model.
Chip & Sarah Model New.skp (9.7 MB)
PS. If you haven’t already, watch the SketchUp Fundamentals series of videos on learn.sketchup.com.
And there’s a new post on the forum here, Watch This Before You Get Started With SketchUp (2021 Update)
which might be worth your while to view too.