I only do this once every three or four years, so can somebody please remind me how to fix it so documents and programs always open with mouse clicks instead of having to use "open with."

Bring up directory of files that includes the one of interest.
Right click on the file (document or whatever).
Select "create shortcut".
When the shortcut has appeared in the file display, drag it onto the desktop.

Thanks, but that's not it.

For example, I can't open folders in Windows Explorer with a click. I have to use the "open with" option.

Hmm. Could it be a matter of association a file extension with the application that's supposed to open it?

Chango,
What version of which Windows are you using?

With XP pro and Windows 7 Home Premium, after I find a folder, all I have to do is double-click to make it open. I can also right-click it once and click the open option that appears. In Windows 7, opening with a single click is available as an option: Go to Knowledge Base and search for open folder to learn how to choose it.

KB for W7 suggests: Click Single-click to open an item (point to select), and then click OK. (To switch back to the standard double-click, click Double-click to open an item (single-click to select).
Seán

Sounds like a wrong registry setting to me. Try this:
1.Start Registry Editor. (start -> Run... -> regedit)

2.Locate the Default value under the following key in the registry:
HKEY_CLASSES_ROOT\Directory\shell

3.Click Modify on the Edit menu.

4.In the File data box, type:
none

5.Click OK.

6.Quit Registry Editor.

Then restart and see if that fixes the problem. If not, it's probably a problem with the (sometimes invisible) autorun.inf

Jeff/CompGuy

OK, I relearned the drill.

In addition to choosing defaults and associations, I had to take one more step when using the "open with" command - checking a box that says "Always open with this program"