So I think that I’ve tracked down the problem.
Let me lead off by saying what the root issue is: We’re not getting current assets and current liabilities totals for a bunch of companies. Meaning it’s in the data. Our AstCur and LiabCur functions just report what we get from CompuStat, and there are more nulls in those fields than I, for one, was expecting.
Here’s where I do expect them: Financial companies – just about all of them, as far as I know, though I’m no expert in financial-firm accounting – those companies that just reported and don’t have complete balance sheets available, and semi-annually-reporting companies (mostly ADRs) in the off season.
What surprised me is that some companies just don’t report current assets and current liabilities. The largest of those is GE. Look at the most recent SEC doc, and the balance sheet doesn’t have a delineated current asset or liability section. (That was the hint that got me over the finish line.)
And yet CapitalIQ gives a current asset line on its site. They calculate it themselves.
So I inserted an Eval into the prior equation:
LiabTotQ=Eval(LiabCurQ!=NA,LiabCurQ,PayablesQ+DbtSTQ+TxPayableQ+LiabCurOtherQ)+LiabNonCurOtherQ+DbtLTQ+TxDfdICQ
Dump that into the screener as a not-equal-to test run today and 881 companies are returned. As I mentioned earlier in the thread, equalities are kind of strange because to the computer 1 is not equal to 1.000000000001, and we might get rounding errors.
So I changed that equality to a ratio and then searched for companies where the equation is more than 0.01% different. The number of companies where the above relationship doesn’t hold drops to three. (COGLF, INVH, and PLYA for the curious. And PLYA didn’t show up in an earlier test for companies more than 0.10% different.)
I don’t think that we’re going to change LiabCurQ or AstCurQ, because they are just database dumps. If you really, really want to correct for this, create custom formulas:
Name:CurrentLiabilities
Formula:
Eval(LiabCurQ!=NA,LiabCurQ,PayablesQ+ DbtSTQ + TxPayableQ+LiabCurOtherQ )
I haven’t tested as extensively on the other side of the sheet, but this should work:
Name:CurrentAssets
Formula:
Eval(AstCurQ!=NA,AstCurQ, CashEquivQ+ RecvblQ + InventoryQ + AstCurOtherQ )
EDIT: Aaron pointed out a slightly more elegant way of doing this, with IsNA. Also, I corrected a couple of other dumb errors. 
Name:CurrentLiabilities
Formula:
IsNA(LiabCurQ,PayablesQ+ DbtSTQ + TxPayableQ+LiabCurOtherQ )
Name:CurrentAssets
Formula:
IsNA(AstCurQ, CashEquivQ+ RecvblQ + InventoryQ + AstCurOtherQ )