When editing a record, if I select a string of text in a field and right click on the mouse to copy the text, the selection collapses to the cursor point.

After selecting text the copy command works from the toolbar button ok.

Is this a bug or something wrong with my installation?

Are you using version 4.2x? Do you have "Check spelling as you type" on for this textbase?

The behavior you describe is a side effect of this feature, and is unfortunately in the third-party spell check library from Wintertree where we cannot address it.