ArcMap 10.1 drop down box selections cause crash

Here are two examples of my problem stated above: 1) With a couple of FCs added to the TOC, use the Effects toolbar drop down box to select a FC; once I do that, ArcMap crashes; 2) With at least one FC added to the TOC, open ArcToolbox > Data Management > Generalization > Dissolve and once that Dissolve window is open, use the drop down box to select a FC in the TOC; once I do that, ArcMap crashes. It happens when making a selection from any drop down box in ArcMap. Selecting to use the 'browse to folder' choice works fine in the Dissolve example, but is not as convenient. I also had this issue with v10.0 and I am using the same computer (just upgraded 10.0 to 10.1).

I no longer believe it might be the ArcGIS installation itself, but rather some Windows-related tie-in to ArcGIS.

Anyone else have this issue, or know what I might look for to resolve it?

Thanks,
Kirk