Extra diagonal extension on inserted clip

[Amnon.S]

For some reason, when inserting a clip through the onscreen shortcuts (from source to timeline) I keep getting this extra blank extension onto a clip, with diagonal lines.

If I just insert normally it doesn't do that. Any hints or tips?

[Joëlle Bh]

Can please tell us what are the sequence settings? You might be opening a sequence with the wrong dimensions

and i want you to check if the guides are on in the program monitor.. click the wrench icon in the Program monitor panel, and go down the the Ruler/Guides options and press clear guides

[Ann Bens]

FAQ: What do I do when I see diagonal lines on clips