Fixing Problems & Issues
 Is there anything wrong with how the SU workspace looks or any abnormal tool function?
Does your computer refuse to open SketchUp?
There may be a deficiency with the
 Graphics Card and/or its driver.

Sometimes there are problems installing SketchUp, sometimes problems are SketchUp bugs, and sometimes problems with SketchUp are symptoms of another computer conflict.
Try Windows Issues or Mac Issues for troubleshooting help
There is Linux help too.

Plugins and Extensions troubleshooting and tips.

There is Dialog Window Issues preventing access to the 3D Warehouse, Extension Warehouse, Add Location, Generate Reports, plugins, and other features require functional webdialogs.

Here is a Checklist of things to do when upgrading to the latest SketchUp release.

And a catch-all for interesting problems and Other Annoyances that come up from time to time with modeling and whatnot.