What is your reputation? Do you have any quests left that you may be able to complete to improve it? (see
Reputation-list-spoiler)
Is it just those 2 imps that have a problem with you, or are other characters neutral/hostile?
What version of the game do you have, CD/DVD or download?
It may be possible to simply replace the character data for the 2 imps in the data.000 file with that from a working save (see
Reviving dead NPCs).
Check your messages (click 'My Stuff' in the top menu bar, then 'My Messages').
