I have a "how to" folder on my computer desktop which I fill with little snippets of information over time. It's handy for those moments when you need to solve a problem but you can't quite recall how you did it last time.

Here are a couple of tips that I find really useful for ArcMap and ArcCatalog:

Tip #1. Three things to try when ArcMap hangs on "add data"

- Try connecting to the VPN you were last connected to. It may be looking for a connection that you can no longer reach.

- Start the "Advanced ArcMap settings" in the Utilities Folder (the default location is along the lines of "C:\Program Files\ArcGIS\Utilities") and click "reset all values to default".

- Go get a cup of coffee. Sometimes waiting helps - if it is looking for a connection that doesn't exist any more, you may just need to let it time out.

Tip #2. How to make ArcCatalog open faster

- Disconnect folders you are not using anymore

- Clear out the Toolbox history:
click the results tab in the Toolbox menu
remove all tool results from previous sessions