Safari interrupts typing search

Lately, when I hit ⌘L to go the address bar and start typing, sometimes Safari will “interrupt” my typing and either:

• do the equivalent of “hitting return”, resulting in a search for whatever I was typing when it interrupted
• “autocomplete” what I was typing based on history, and then “hit return”, going to the page without me telling it to

This is driving me crazy. Does anybody know anything about this problem?

My setup:

• 13-inch MacBook Pro (mid-2010)
• Mountain Lion 10.8.2
• Safari 6.0.2