aarrrgh i dont understand what is going on, thousands of coins are missing and there is no transaction showing what happened

maybe someone here infinitely smarter than me can think up what this could be ? im stumped.
1. compiled the wallet on monday 27th
2. mined 7000 kh/s @ minebig for days
3. got about 6,000 CASH after a few days, in our wallet. confirmed, confirmations, everything happy.
: these were sent to our wallet as they were mined, so every hour it was climbing... for days.
(edit) 3.5:opened an openex account and sent 100cash just as a test, it arrived in openex and i withdrew it back to my wallet and it came back. success or so i thought.
4. looked at balance yesterday (day after doing an in/out with openex) and it was suddenly under 600 !!
5. did a "cashd listtransactions" (shows last 10 only) and there is no outgoing transactions.
6. did a "cashd listtransactions 100000" (to show ALL transactions) and there is nothing being sent!
: so they are not stolen, or atleast in my understanding of 'stolen'.
7. wrote a script to take the json from that and 'add it up' myself, and it only adds up to the 600 balance! wtf ... (with no negative numbers !)
how could the wallet have thousands in it, deposited over a period of days from minebig, then suddenly drop back to a lowly 600 for no apparent reason ?
so i took a copy of the wallet.dat, recompiled from source (fresh download), resynced with the network, and still only 600.
really not understanding why/what/how ... weird weird weird.
does that mean i got 'forked' or is that just 'f..ked' lol

./Cashd getinfo
{
"version" : "v1.0.0.0-g32a928e-CASH",
"protocolversion" : 70000,
"walletversion" : 60000,
"balance" : 876.69554400,
"newmint" : 0.00000000,
"stake" : 0.00000000,
"blocks" : 16574,
"moneysupply" : 412989.01368200,
"connections" : 58,
"proxy" : "",
"ip" : "46.4.95.176",
"difficulty" : 5.41119469,
"testnet" : false,
"keypoololdest" : 1390818327,
"keypoolsize" : 102,
"paytxfee" : 0.00100000,
"errors" : "WARNING: Checkpoint is too old. Redownload Blockchain. If warning persist contact the Development Team"
}