Until the beginning of this year, i mined Dime with the original wallet (v0.8.3.14-g09e437b-beta) and i can tell you that neither pool or solo mining created any orphans on a regular basis.
I had many millions of this coin, but there were 0 exchanges. Then the coin got "re-developed" and put on an exchange, but strangely enough the exchange couldn't accept my coins.
So basically if you are all having the problems you are saying, then clearly the dev has done something untoward with the new wallet.
I have no idea what can be done, if anything.
If anyone wants to do a test sending some coins to my wallet to see if they orphan or do anything strange, i will return (minus any fees of course).
My current Wallet is version "v0.8.3.14-g09e437b-beta"
My current block height is "2880763" @ Tue 22. May 08:31:03 2018
This has been synced from 0
Personally looking at all the issues you are having, the crazy diff (was under 200 when i was mining - i was making 10 mil coins a day easy), the price, i'd say this coin is well and truely dead.
Go to the wallets page on the website, close your wallet and reinstall, but be sure to copy/save/back up your wallet.dat file first and things will be ok, I use livecoin and have had no issues