Blinking box for text delete/insert?

One vexing thing I've found since getting my MB on Saturday is a funky behavior when deleting & re-entering text. I'll double-tap the trackpad, or single-click the corner, select a block of text, then hit Delete. When I try to type, I'll get a single-character block of flashing text, and when I type letters, they replace each other. If I type "cut" I get C, which is replaced by the U, then the T, but the entire word never appears. I usually have to put focus on another window or field to get back to "regular" text entry.

Any idea what function I've invoked, and how to avoid?

Which application are you using when this occurs? You stated "entering and re-entering text". Are you using TextEdit? MS Word? ?

It sounds like you're using "overtype" mode rather than "replace" when entering text. That function is usually controlled from within application.

Regards.

Thanks for the reply!

This mostly happens in Safari, specifically in a Gmail message. I think "overtype" is an accurate description of what's happening.

Try hitting the Insert key on your keyboard. This has solved the problem for me in the past, though not in Safari.