I can't type in a timecode in the source monitor

When I load a clip into the source window and try to type in a timecode so I can jump to a specific spot in the clip, the timecode I type in appears but doesn' take and goes back to the starting timecode of the clip. I have restarted Premiere, turned off the computer and relaunched, no luck. However, when I came back the next day, it worked fine, but the problem repeated later in the day with another clip. I have Adobe Creative Suite and this is the latest update of Premiere.