Are all of your transactions from the end of 2013/early 2014?

It's possible that you were mining one of the many forks that developed in the early weeks after CAT launched.  The founder launched the coin at a very low difficulty and used the same difficulty adjustment as BTC.  There was a LOT of hash on the coin at launch and more than one million CAT were mined in the first weeks - and there were a lot of forks.  Do you remember how you mined your coins?

No worries about the PM Alex.

We cannot use the earlier wallets as the database has changed at least once, and we've had at least two major upgrades that caused forks since V0.8xxx

Ok...let's start fresh.   The wallet binary doesn't install, so you don't have to do anything there.  Let's erase the blockchain and let it rebuild and see what happens.

First, an overview:
- stop the wallet (and remove any earlier catcoin wallets - you'll stay with 9.3.0)
- delete everything except the wallet.dat
- start the wallet and let it reload

Details...

Press the windows button in the lower left, and enter %appdata% in the search box (this opens the hidden appdata folder)
Navigate to AppData > Roaming > Catcoin
Inside, you'll see two folders called 'blocks' and 'chainstate'.  You'll also see a number of files including one called 'wallet.dat'
Delete everything there - but do not delete wallet.dat - that's where your coins are stored

Once the folder is cleared of everything except wallet.dat, exit the file explorer and start the 9.3.0 wallet.  The wallet will connect to the seed nodes and quickly download the entire blockchain.