Ehhh ...mega...codec...pack...
...Eeeek
I've always and consistenly advised against using codec-packs.
Lots of users seem to think that more is better. IMHO: to the contrary!
Anyhow... version and buildnr you're using?
Perhaps you redefined any hotkeys?
What hotkeys do you use?
"Remember movie settings" unchecked?
"Remember Pan-Scan settings" & "Remember zoom" unchecked?
What happens if you depress [5] on numeric keyboard?