Can't slip my clips within the timeline, receiving odd screen when I try

Hi guys,

On my PC today my Premiere Pro suddenly began acting very strange. Suddenly I cannot pull a clip into the timeline from the project window & clips that are in the timeline cannot be slipped and moved around; when I try, a screen with 'insert before/overwrite/insert after etc. is seen in the viewer. 

I've closed the app, tried opening it again whilst holding alt and resetting the preferences; I've uninstalled and reinstalled premiere pro, reversed recent updates from OneDrive in case that was messing with it.  Nothing seems to be working, wondering if anyone might have some idea as to what is up.  I'd rather not switch over to Davinci, but I've got work to do.

Thanks guys for your consideration.