It got so bad I had around 20 units disband on me due to lack of money. The drop was very noticable on the Power graph.

However, through some shrewd tech trading and a Wonder being converted into gold due to another civ finishing first, my treasury rose, I added courthouses, researched currency and recovered from the depression to invade the mighty China... that is currently where it stands.

This is as hannibil: First i get hinduism, then I go for pottery. I build cottages, go for priesthood so you can build the oracle, but don't build it yet. Get judaism and writing. By this time you should have 2 or 3 cities at least. the third city should make you go down 1, but by finding huts you should have a good buffer to keep you at 100%. Now build the stonehedge if you haven't already, and then build the oracle. Get theocracy, with luck you should have a holy city for judaism (a maybe), hinduism, and christianity. At this point you should pump out a great profit before needing to go down science. However if your cities are falling behind, you may be forced to build a couple more and reduce your science to 90%, but not any lower. the great prophet is born and build the wonder who's realigion is spread the most, one of your three founding realigions. This should give you enough money to get your science up to 100% and every time you start going negative because of cities, simply spread your realigion. I usually build the temple of artimites too, so you should get a second prophet out quickly, who can help you even further.