I wanted to waste some time in a skirmish game and just close the borders and build the biggest strongest army I could before attacking, but as the game gets long some stuff gets broken (I can't order to dig something anymore and imps won't take creatures fainted in combat pits to lairs), it's like my imps broke;

useless to reload, restart the game or use the repair tool

Has anybody had the same issues and is there a way to prevent/fix them?

The enemy hasn't perhaps surrounded you with their walls have they? Or built walls where you're trying to dig? That might happen in a long game. You need a spell to destroy the walls in such a case. Otherwise you could try possessing an imp and dig manually.

Not sure about the pit->lair issue though.

No I can't really order to dig anything, not even my gem/gold stuff

It doesn't stay "light blue" after I click

Have you tried digging with a possessed imp? Or perhaps just kill every single imp until you have none left and then summon a new one?

tried both, didn't work

Sorry then I really don't know. I quickly checked for known bugs but didn't see anything. Perhaps there is some kind of large dig limit in the game that was exceeded and now your imps are bugging out :P Or perhaps something else entirely :\

The only other thing I can think of trying is to install the unofficial patch
http://www.gogwiki.com/wiki/Dungeon_Keeper_2

actually mining with a possessed imp kinda works, but it doesn't solve problems like gold mining

I know this is an old post, but I have the exact same problem. Has anyone a solution for it?
I would greatly appreciate continuing my long lasting saved game.

Any chance you have an awful lot of gold? If you have too much gold and/or 'things' then the game appears to be unable to spawn more, which is a prerequesite to complete the mining of a gem block or gold block, for example. Things start going reeeeeeally weird when you have a lot of money. I don't think I've noticed it happen outside of levels like Flowerhat or Belbata though as those are the ones that you can just mess about and make a silly amount of gold if you really want to.

Just get rid of an awful lot of your gold and things should go back to normal (I appreciate your post was nearly 5 years ago)